diff --git a/README.md b/README.md
index 951c029a5..c2355ea0b 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ Zen is a firefox-based browser with the aim of pushing your productivity to a ne
 ### Firefox Versions
 
 - [`Release`](https://zen-browser.app/download) - Is currently built using Firefox version `155.0.1`!
-- [`Twilight`](https://zen-browser.app/download?twilight) - Is currently built using Firefox version `RC 155.0.1`!
+- [`Twilight`](https://zen-browser.app/download?twilight) - Is currently built using Firefox version `RC 156.0`!
 
 ### Contributing
 
diff --git a/build/firefox-cache/l10n-last-commit-hash b/build/firefox-cache/l10n-last-commit-hash
index d80addb07..a8635172d 100644
--- a/build/firefox-cache/l10n-last-commit-hash
+++ b/build/firefox-cache/l10n-last-commit-hash
@@ -1 +1 @@
-b6d45eac914fd4886c9b6e5f1447f613771228ff
\ No newline at end of file
+931c2f71dc0b1e11668a5ca165dd75e2e4297174
\ No newline at end of file
diff --git a/src/browser/base/content/navigator-toolbox-inc-xhtml.patch b/src/browser/base/content/navigator-toolbox-inc-xhtml.patch
index 6bfa00678..9c1a5c529 100644
--- a/src/browser/base/content/navigator-toolbox-inc-xhtml.patch
+++ b/src/browser/base/content/navigator-toolbox-inc-xhtml.patch
@@ -1,5 +1,5 @@
 diff --git a/browser/base/content/navigator-toolbox.inc.xhtml b/browser/base/content/navigator-toolbox.inc.xhtml
-index dd2f391096968564086911c532f696dc7ffb8ae1..c968e5f0ebb5f0151fb124bafe10d8d5361e060f 100644
+index a76bb7aae7636c07989a4acb35281777d3103505..c5eafbdad5270cd9926ed4f1d850d134440d775b 100644
 --- a/browser/base/content/navigator-toolbox.inc.xhtml
 +++ b/browser/base/content/navigator-toolbox.inc.xhtml
 @@ -2,7 +2,7 @@
@@ -26,7 +26,7 @@ index dd2f391096968564086911c532f696dc7ffb8ae1..c968e5f0ebb5f0151fb124bafe10d8d5
    <toolbar id="TabsToolbar"
             class="browser-toolbar browser-titlebar"
             fullscreentoolbar="true"
-@@ -54,6 +58,8 @@
+@@ -56,6 +60,8 @@
            <html:sidebar-pins-promo id="drag-to-pin-promo-card"></html:sidebar-pins-promo>
            <arrowscrollbox id="pinned-tabs-container" orient="horizontal" clicktoscroll=""></arrowscrollbox>
            <splitter orient="vertical" id="vertical-pinned-tabs-splitter" resizebefore="sibling" resizeafter="none" hidden="true"/>
@@ -35,7 +35,7 @@ index dd2f391096968564086911c532f696dc7ffb8ae1..c968e5f0ebb5f0151fb124bafe10d8d5
            <hbox class="tab-drop-indicator" hidden="true"/>
            <arrowscrollbox id="tabbrowser-arrowscrollbox" orient="horizontal" flex="1" clicktoscroll="" scrolledtostart="" scrolledtoend="">
              <tab is="tabbrowser-tab" class="tabbrowser-tab" selected="" visuallyselected="" fadein=""/>
-@@ -73,6 +79,7 @@
+@@ -75,6 +81,7 @@
                                tooltip="dynamic-shortcut-tooltip"
                                data-l10n-id="tabs-toolbar-new-tab"/>
            <html:span id="tabbrowser-tab-a11y-desc" hidden="true"/>
@@ -43,7 +43,7 @@ index dd2f391096968564086911c532f696dc7ffb8ae1..c968e5f0ebb5f0151fb124bafe10d8d5
          </tabs>
  
          <toolbarbutton id="new-tab-button"
-@@ -99,9 +106,10 @@
+@@ -102,9 +109,10 @@
  
      <toolbarbutton class="content-analysis-indicator toolbarbutton-1 content-analysis-indicator-icon"/>
  
@@ -54,4 +54,4 @@ index dd2f391096968564086911c532f696dc7ffb8ae1..c968e5f0ebb5f0151fb124bafe10d8d5
 +</hbox>
  
    <toolbar id="nav-bar"
-            class="browser-toolbar chromeclass-location"
+            class="browser-toolbar"
diff --git a/src/browser/components/customizableui/CustomizableUI-sys-mjs.patch b/src/browser/components/customizableui/CustomizableUI-sys-mjs.patch
index ba2213692..411cc1b90 100644
--- a/src/browser/components/customizableui/CustomizableUI-sys-mjs.patch
+++ b/src/browser/components/customizableui/CustomizableUI-sys-mjs.patch
@@ -1,5 +1,5 @@
 diff --git a/browser/components/customizableui/CustomizableUI.sys.mjs b/browser/components/customizableui/CustomizableUI.sys.mjs
-index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa13303d3a3 100644
+index 875f8b03d979353ef44a57c15ef1ae09d33ab730..3d6e092e7ed126cdee8c32229df2cfa13303d3a3 100644
 --- a/browser/components/customizableui/CustomizableUI.sys.mjs
 +++ b/browser/components/customizableui/CustomizableUI.sys.mjs
 @@ -13,6 +13,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
@@ -19,7 +19,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
        },
        false
      );
-@@ -362,27 +363,23 @@ var CustomizableUIInternal = {
+@@ -362,20 +363,15 @@ var CustomizableUIInternal = {
        "back-button",
        "forward-button",
        "stop-reload-button",
@@ -41,27 +41,29 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      this.registerArea(
        CustomizableUI.AREA_NAVBAR,
        {
-         type: CustomizableUI.TYPE_TOOLBAR,
+@@ -383,9 +379,6 @@ var CustomizableUIInternal = {
          overflowable: true,
          defaultPlacements: navbarPlacements,
--        verticalTabsDefaultPlacements: ["alltabs-button", "ai-window-toggle"],
-+        verticalTabsDefaultPlacements: [
-+        ],
+         verticalTabsDefaultPlacements: [
+-          "alltabs-button",
+-          "smartwindow-group-tabs-button",
+-          "ai-window-toggle",
+         ],
          defaultCollapsed: false,
        },
-       true
-@@ -406,10 +403,6 @@ var CustomizableUIInternal = {
+@@ -410,11 +403,6 @@ var CustomizableUIInternal = {
          type: CustomizableUI.TYPE_TOOLBAR,
          defaultPlacements: [
            "tabbrowser-tabs",
 -          "new-tab-button",
 -          "spring",
 -          "alltabs-button",
+-          "smartwindow-group-tabs-button",
 -          "ai-window-toggle",
          ],
          verticalTabsDefaultPlacements: [],
          defaultCollapsed: null,
-@@ -502,6 +495,7 @@ var CustomizableUIInternal = {
+@@ -507,6 +495,7 @@ var CustomizableUIInternal = {
        CustomizableUI.AREA_NAVBAR,
        CustomizableUI.AREA_BOOKMARKS,
        CustomizableUI.AREA_TABSTRIP,
@@ -69,7 +71,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      ]);
      if (AppConstants.platform != "macosx") {
        toolbars.add(CustomizableUI.AREA_MENUBAR);
-@@ -1334,6 +1328,9 @@ var CustomizableUIInternal = {
+@@ -1339,6 +1328,9 @@ var CustomizableUIInternal = {
          placements = gPlacements.get(area);
        }
  
@@ -79,7 +81,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
        // For toolbars that need it, mark as dirty.
        let defaultPlacements = areaProperties.get("defaultPlacements");
        if (
-@@ -1842,7 +1839,6 @@ var CustomizableUIInternal = {
+@@ -1847,7 +1839,6 @@ var CustomizableUIInternal = {
          lazy.log.info(
            "Widget " + aWidgetId + " not found, unable to remove from " + aArea
          );
@@ -87,7 +89,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
        }
  
        this.notifyDOMChange(widgetNode, null, container, true, () => {
-@@ -1852,7 +1848,7 @@ var CustomizableUIInternal = {
+@@ -1857,7 +1848,7 @@ var CustomizableUIInternal = {
          // We also need to remove the panel context menu if it's there:
          this.ensureButtonContextMenu(widgetNode);
          if (gPalette.has(aWidgetId) || this.isSpecialWidget(aWidgetId)) {
@@ -96,7 +98,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
          } else {
            window.gNavToolbox.palette.appendChild(widgetNode);
          }
-@@ -2020,16 +2016,16 @@ var CustomizableUIInternal = {
+@@ -2025,16 +2016,16 @@ var CustomizableUIInternal = {
          elem.setAttribute("skipintoolbarset", "true");
        }
      }
@@ -116,7 +118,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      // Handle initial state of vertical tabs.
      if (isVerticalTabs) {
        // Show the vertical tabs toolbar
-@@ -2271,6 +2267,10 @@ var CustomizableUIInternal = {
+@@ -2276,6 +2267,10 @@ var CustomizableUIInternal = {
     *   The identifier string of the area that aNode is being inserted into.
     */
    insertWidgetBefore(aNode, aNextNode, aContainer, aAreaId) {
@@ -127,7 +129,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      this.notifyDOMChange(aNode, aNextNode, aContainer, false, () => {
        this.setLocationAttributes(aNode, aAreaId);
        aContainer.insertBefore(aNode, aNextNode);
-@@ -4647,7 +4647,7 @@ var CustomizableUIInternal = {
+@@ -4652,7 +4647,7 @@ var CustomizableUIInternal = {
     * For all registered areas, builds those areas to reflect the current
     * placement state of all widgets.
     */
@@ -136,7 +138,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      for (let [areaId, areaNodes] of gBuildAreas) {
        let placements = gPlacements.get(areaId);
        let isFirstChangedToolbar = true;
-@@ -4658,7 +4658,7 @@ var CustomizableUIInternal = {
+@@ -4663,7 +4658,7 @@ var CustomizableUIInternal = {
          if (area.get("type") == CustomizableUI.TYPE_TOOLBAR) {
            let defaultCollapsed = area.get("defaultCollapsed");
            let win = areaNode.documentGlobal;
@@ -145,7 +147,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
              win.setToolbarVisibility(
                areaNode,
                typeof defaultCollapsed == "string"
-@@ -5971,6 +5971,7 @@ export var CustomizableUI = {
+@@ -5976,6 +5971,7 @@ export var CustomizableUI = {
    unregisterArea(aName, aDestroyPlacements) {
      CustomizableUIInternal.unregisterArea(aName, aDestroyPlacements);
    },
@@ -153,7 +155,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
    /**
     * Add a widget to an area.
     * If the area to which you try to add is not known to CustomizableUI,
-@@ -7946,7 +7947,9 @@ class OverflowableToolbar {
+@@ -7951,7 +7947,9 @@ class OverflowableToolbar {
          );
  
          if (webExtList && CustomizableUI.isWebExtensionWidget(child.id)) {
@@ -163,7 +165,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
            webExtList.insertBefore(child, webExtList.firstElementChild);
          } else {
            child.setAttribute("cui-anchorid", this.#defaultListButton.id);
-@@ -7995,6 +7998,7 @@ class OverflowableToolbar {
+@@ -8000,6 +7998,7 @@ class OverflowableToolbar {
        return aElement.getBoundingClientRect().width;
      }
  
@@ -171,7 +173,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      function sumChildrenInlineSize(aParent, aExceptChild = null) {
        let sum = 0;
        for (let child of aParent.children) {
-@@ -8006,7 +8010,10 @@ class OverflowableToolbar {
+@@ -8011,7 +8010,10 @@ class OverflowableToolbar {
          ) {
            continue;
          }
@@ -183,7 +185,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
          if (child != aExceptChild) {
            sum += getInlineSize(child);
          }
-@@ -8030,11 +8037,11 @@ class OverflowableToolbar {
+@@ -8035,11 +8037,11 @@ class OverflowableToolbar {
          parseFloat(style.paddingLeft) -
          parseFloat(style.paddingRight) -
          toolbarChildrenWidth;
@@ -197,7 +199,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      });
  
      lazy.log.debug(
-@@ -8049,7 +8056,39 @@ class OverflowableToolbar {
+@@ -8054,7 +8056,39 @@ class OverflowableToolbar {
        Math.max(targetWidth, targetChildrenWidth)
      );
      totalAvailWidth = Math.ceil(totalAvailWidth);
@@ -238,7 +240,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      return { isOverflowing, targetContentWidth, totalAvailWidth };
    }
  
-@@ -8110,7 +8149,11 @@ class OverflowableToolbar {
+@@ -8115,7 +8149,11 @@ class OverflowableToolbar {
              return;
            }
          }
@@ -251,7 +253,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
            lazy.log.debug(
              `Need ${minSize} but width is ${totalAvailWidth} so bailing`
            );
-@@ -8143,7 +8186,7 @@ class OverflowableToolbar {
+@@ -8148,7 +8186,7 @@ class OverflowableToolbar {
          }
        }
        if (!inserted) {
@@ -260,7 +262,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
        }
        child.removeAttribute("cui-anchorid");
        child.removeAttribute("overflowedItem");
-@@ -8269,6 +8312,9 @@ class OverflowableToolbar {
+@@ -8274,6 +8312,9 @@ class OverflowableToolbar {
     *   if no such list exists.
     */
    get #webExtList() {
@@ -270,7 +272,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      if (!this.#webExtListRef) {
        let targetID = this.#toolbar.getAttribute("addon-webext-overflowtarget");
        if (!targetID) {
-@@ -8280,6 +8326,9 @@ class OverflowableToolbar {
+@@ -8285,6 +8326,9 @@ class OverflowableToolbar {
        let win = this.#toolbar.documentGlobal;
        let { panel } = win.gUnifiedExtensions;
        this.#webExtListRef = panel.querySelector(`#${targetID}`);
@@ -280,7 +282,7 @@ index 6d1885a54815d10b3a4e79f7e5acd61ab3abb159..3d6e092e7ed126cdee8c32229df2cfa1
      }
      return this.#webExtListRef;
    }
-@@ -8488,7 +8537,7 @@ class OverflowableToolbar {
+@@ -8493,7 +8537,7 @@ class OverflowableToolbar {
          break;
        }
        case "mousedown": {
diff --git a/src/browser/components/sessionstore/SessionFile-sys-mjs.patch b/src/browser/components/sessionstore/SessionFile-sys-mjs.patch
index 6c4ad1523..e663bc894 100644
--- a/src/browser/components/sessionstore/SessionFile-sys-mjs.patch
+++ b/src/browser/components/sessionstore/SessionFile-sys-mjs.patch
@@ -1,16 +1,16 @@
 diff --git a/browser/components/sessionstore/SessionFile.sys.mjs b/browser/components/sessionstore/SessionFile.sys.mjs
-index 5580838acd72bf0e1189d367984859529d89f5b4..e5fa6076a9cc6ada016ccc4e129cad455010a522 100644
+index 370e5c105c3d9bee05c2d9d7b63d0ee45b8331e1..1c37c19794ebe863a25f780e9a74d63526b929d7 100644
 --- a/browser/components/sessionstore/SessionFile.sys.mjs
 +++ b/browser/components/sessionstore/SessionFile.sys.mjs
-@@ -22,6 +22,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
-   RunState: "resource:///modules/sessionstore/RunState.sys.mjs",
-   SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
-   SessionWriter: "resource:///modules/sessionstore/SessionWriter.sys.mjs",
+@@ -25,6 +25,7 @@ const lazy = XPCOMUtils.declareLazy({
+     "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
+   SessionWriter:
+     "moz-src:///browser/components/sessionstore/SessionWriter.sys.mjs",
 +  ZenSessionStore: "resource:///modules/zen/ZenSessionManager.sys.mjs",
  });
  
  const PREF_UPGRADE_BACKUP = "browser.sessionstore.upgradeBackup.latestBuildID";
-@@ -381,7 +382,7 @@ var SessionFileInternal = {
+@@ -384,7 +385,7 @@ var SessionFileInternal = {
      this._readOrigin = result.origin;
  
      result.noFilesFound = noFilesFound;
diff --git a/src/browser/components/sessionstore/SessionSaver-sys-mjs.patch b/src/browser/components/sessionstore/SessionSaver-sys-mjs.patch
index 48e7e2c9b..96c225f90 100644
--- a/src/browser/components/sessionstore/SessionSaver-sys-mjs.patch
+++ b/src/browser/components/sessionstore/SessionSaver-sys-mjs.patch
@@ -1,11 +1,11 @@
 diff --git a/browser/components/sessionstore/SessionSaver.sys.mjs b/browser/components/sessionstore/SessionSaver.sys.mjs
-index 9141793550f7c7ff6aa63d4c85bf571b4499e2d0..6906fd9be7ae6ca4316133e0d6552b797c54a7ec 100644
+index 1f26bc5fdb83f55bdf0b9b7d01fafe1cd37f77f4..5916f741d0fa04c392dcdd10f843e595fe5e058c 100644
 --- a/browser/components/sessionstore/SessionSaver.sys.mjs
 +++ b/browser/components/sessionstore/SessionSaver.sys.mjs
-@@ -20,6 +20,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
-   SessionFile: "resource:///modules/sessionstore/SessionFile.sys.mjs",
-   SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
-   sessionStoreLogger: "resource:///modules/sessionstore/SessionLogger.sys.mjs",
+@@ -20,6 +20,7 @@ const lazy = XPCOMUtils.declareLazy({
+     "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
+   sessionStoreLogger:
+     "moz-src:///browser/components/sessionstore/SessionLogger.sys.mjs",
 +  ZenSessionStore: "resource:///modules/zen/ZenSessionManager.sys.mjs",
  });
  
diff --git a/src/browser/components/sessionstore/SessionStartup-sys-mjs.patch b/src/browser/components/sessionstore/SessionStartup-sys-mjs.patch
index 61bdf8f93..bb691e449 100644
--- a/src/browser/components/sessionstore/SessionStartup-sys-mjs.patch
+++ b/src/browser/components/sessionstore/SessionStartup-sys-mjs.patch
@@ -1,16 +1,16 @@
 diff --git a/browser/components/sessionstore/SessionStartup.sys.mjs b/browser/components/sessionstore/SessionStartup.sys.mjs
-index 86600ffb5178599ab23270a964064ca657a3283f..70d7b5c7d69d3700475d663b595052264c67d351 100644
+index 919d4536c5462603346684bbe26794ae9279b517..5a8fae0708e4a9a82c5e85f8a473ebaeafebe71f 100644
 --- a/browser/components/sessionstore/SessionStartup.sys.mjs
 +++ b/browser/components/sessionstore/SessionStartup.sys.mjs
-@@ -40,6 +40,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
-   StartupPerformance:
-     "resource:///modules/sessionstore/StartupPerformance.sys.mjs",
-   sessionStoreLogger: "resource:///modules/sessionstore/SessionLogger.sys.mjs",
+@@ -41,6 +41,7 @@ const lazy = XPCOMUtils.declareLazy({
+     "moz-src:///browser/components/sessionstore/StartupPerformance.sys.mjs",
+   sessionStoreLogger:
+     "moz-src:///browser/components/sessionstore/SessionLogger.sys.mjs",
 +  ZenSessionStore: "resource:///modules/zen/ZenSessionManager.sys.mjs",
  });
  
  const STATE_RUNNING_STR = "running";
-@@ -85,7 +86,7 @@ export var SessionStartup = {
+@@ -86,7 +87,7 @@ export var SessionStartup = {
      }
  
      // do not need to initialize anything in auto-started private browsing sessions
@@ -19,7 +19,7 @@ index 86600ffb5178599ab23270a964064ca657a3283f..70d7b5c7d69d3700475d663b59505226
        this._initialized = true;
        gOnceInitializedDeferred.resolve();
        return;
-@@ -179,6 +180,8 @@ export var SessionStartup = {
+@@ -180,6 +181,8 @@ export var SessionStartup = {
        this._initialState = parsed;
      }
  
@@ -28,7 +28,7 @@ index 86600ffb5178599ab23270a964064ca657a3283f..70d7b5c7d69d3700475d663b59505226
      if (this._initialState == null) {
        // No valid session found.
        this._sessionType = this.NO_SESSION;
-@@ -276,6 +279,8 @@ export var SessionStartup = {
+@@ -277,6 +280,8 @@ export var SessionStartup = {
          `Previous shutdown ok? ${this._previousSessionCrashed}, reason: ${previousSessionCrashedReason}`
        );
  
@@ -37,7 +37,7 @@ index 86600ffb5178599ab23270a964064ca657a3283f..70d7b5c7d69d3700475d663b59505226
        Services.obs.addObserver(this, "sessionstore-windows-restored", true);
  
        if (this.sessionType == this.NO_SESSION) {
-@@ -336,12 +341,7 @@ export var SessionStartup = {
+@@ -337,12 +342,7 @@ export var SessionStartup = {
    isAutomaticRestoreEnabled() {
      if (this._resumeSessionEnabled === null) {
        this._resumeSessionEnabled =
@@ -51,7 +51,7 @@ index 86600ffb5178599ab23270a964064ca657a3283f..70d7b5c7d69d3700475d663b59505226
      }
  
      return this._resumeSessionEnabled;
-@@ -354,8 +354,7 @@ export var SessionStartup = {
+@@ -355,8 +355,7 @@ export var SessionStartup = {
     */
    willRestore() {
      return (
diff --git a/src/browser/components/sessionstore/SessionStore-sys-mjs.patch b/src/browser/components/sessionstore/SessionStore-sys-mjs.patch
index bc0b5a625..6c6b73e0c 100644
--- a/src/browser/components/sessionstore/SessionStore-sys-mjs.patch
+++ b/src/browser/components/sessionstore/SessionStore-sys-mjs.patch
@@ -1,8 +1,8 @@
 diff --git a/browser/components/sessionstore/SessionStore.sys.mjs b/browser/components/sessionstore/SessionStore.sys.mjs
-index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2eaa1afed 100644
+index 52fc803050cd257d6de52b1e4a92f3211cbaba88..a9841832ddce540dc0f9b14c29e5eadac7510935 100644
 --- a/browser/components/sessionstore/SessionStore.sys.mjs
 +++ b/browser/components/sessionstore/SessionStore.sys.mjs
-@@ -126,6 +126,11 @@ const TAB_EVENTS = [
+@@ -111,6 +111,11 @@ const TAB_EVENTS = [
    "TabSplitViewActivate",
    "SplitViewRemoved",
    "SplitViewCreated",
@@ -14,16 +14,39 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
  ];
  
  const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
-@@ -198,6 +203,8 @@ ChromeUtils.defineESModuleGetters(lazy, {
-   TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
-   TabStateFlusher: "resource:///modules/sessionstore/TabStateFlusher.sys.mjs",
+@@ -185,6 +190,8 @@ const lazy = XPCOMUtils.declareLazy({
+   TabStateFlusher:
+     "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs",
    setTimeout: "resource://gre/modules/Timer.sys.mjs",
 +  ZenSessionStore: "resource:///modules/zen/ZenSessionManager.sys.mjs",
 +  ZenWindowSync: "resource:///modules/zen/ZenWindowSync.sys.mjs",
- });
+   blankURI: () => Services.io.newURI("about:blank"),
+   gRestoreWindowsToVirtualDesktop: {
+     pref: "browser.sessionstore.restore_windows_to_virtual_desktop",
+@@ -348,6 +355,22 @@ class _SessionStore {
+     return this.#shouldRestoreLastSession;
+   }
  
- ChromeUtils.defineLazyGetter(lazy, "blankURI", () => {
-@@ -1314,10 +1321,7 @@ var SessionStoreInternal = {
++  get _windows() {
++    return this.#windows;
++  }
++
++  get _browserWindows() {
++    return this.#browserWindows;
++  }
++
++  set _deferredInitialState(aState) {
++    this.#deferredInitialState = aState;
++  }
++
++  initializeWindow(aWindow, aInitialState) {
++    this.#initializeWindow(aWindow, aInitialState);
++  }
++
+   // whether we will potentially be restoring the session
+   // more than once without Firefox restarting in between
+   #restoreWithoutRestart = false;
+@@ -515,10 +538,7 @@ class _SessionStore {
     */
    get willAutoRestore() {
      return (
@@ -33,9 +56,9 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
 -          BROWSER_STARTUP_RESUME_SESSION)
 +      true
      );
-   },
+   }
  
-@@ -2005,6 +2009,11 @@ var SessionStoreInternal = {
+@@ -1215,6 +1235,11 @@ class _SessionStore {
        case "TabPinned":
        case "TabUnpinned":
        case "SwapDocShells":
@@ -44,47 +67,47 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
 +      case "TabMove":
 +      case "TabGroupMoved":
 +      case "ZenWorkspaceDataChanged":
-         this.saveStateDelayed(win);
+         this.#saveStateDelayed(win);
          break;
        case "TabGroupCreate":
-@@ -2114,6 +2123,10 @@ var SessionStoreInternal = {
-       this._windows[aWindow.__SSi].isTaskbarTab = true;
+@@ -1341,6 +1366,10 @@ class _SessionStore {
+       this.#windows[aWindow.__SSi].isTaskbarTab = true;
      }
  
 +    if (aWindow.document.documentElement.hasAttribute("zen-unsynced-window")) {
-+      this._windows[aWindow.__SSi].isZenUnsynced = true;
++      this.#windows[aWindow.__SSi].isZenUnsynced = true;
 +    }
 +
      if (lazy.AIWindow.isAIWindowActiveAndEnabled(aWindow)) {
-       this._windows[aWindow.__SSi].isAIWindow = true;
+       this.#windows[aWindow.__SSi].isAIWindow = true;
      }
-@@ -2150,7 +2163,7 @@ var SessionStoreInternal = {
-     let isTaskbarTab = this._windows[aWindow.__SSi].isTaskbarTab;
+@@ -1377,7 +1406,7 @@ class _SessionStore {
+     let isTaskbarTab = this.#windows[aWindow.__SSi].isTaskbarTab;
      // A regular window is not a private window, taskbar tab window, or popup window
      let isRegularWindow =
 -      !isPrivateWindow && !isTaskbarTab && aWindow.toolbar.visible;
-+      !isPrivateWindow && !isTaskbarTab && aWindow.toolbar.visible && !this._windows[aWindow.__SSi].isZenUnsynced;
++      !isPrivateWindow && !isTaskbarTab && aWindow.toolbar.visible && !this.#windows[aWindow.__SSi].isZenUnsynced;
  
      // perform additional initialization when the first window is loading
      if (lazy.RunState.isStopped) {
-@@ -2162,7 +2175,7 @@ var SessionStoreInternal = {
+@@ -1389,7 +1418,7 @@ class _SessionStore {
          // to disk to NOW() to enforce a full interval before the next write.
          lazy.SessionSaver.updateLastSaveTime();
  
 -        if (isPrivateWindow || isTaskbarTab) {
 +        if (isPrivateWindow || isTaskbarTab || aWindow.document.documentElement.hasAttribute("zen-unsynced-window")) {
-           this._log.debug(
+           this.#log.debug(
              "initializeWindow, the window is private or a web app. Saving SessionStartup.state for possibly restoring later"
            );
-@@ -2206,6 +2219,7 @@ var SessionStoreInternal = {
+@@ -1433,6 +1462,7 @@ class _SessionStore {
            null,
            "sessionstore-one-or-no-tab-restored"
          );
 +        lazy.ZenSessionStore.onNewEmptySession(aWindow);
-         this._deferredAllWindowsRestored.resolve();
+         this.#deferredAllWindowsRestored.resolve();
        }
-       // this window was opened by _openWindowWithState
-@@ -2255,7 +2269,6 @@ var SessionStoreInternal = {
+       // this window was opened by #openWindowWithState
+@@ -1482,7 +1512,6 @@ class _SessionStore {
        if (closedWindowState) {
          let newWindowState;
          if (
@@ -92,25 +115,25 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
            !lazy.SessionStartup.willRestore()
          ) {
            // We want to split the window up into pinned tabs and unpinned tabs.
-@@ -2291,6 +2304,7 @@ var SessionStoreInternal = {
+@@ -1518,6 +1547,7 @@ class _SessionStore {
          }
  
          if (newWindowState) {
 +          lazy.ZenSessionStore.onRestoringClosedWindow(newWindowState);
            // Ensure that the window state isn't hidden
-           this._restoreCount = 1;
+           this.#restoreCount = 1;
            let state = { windows: [newWindowState] };
-@@ -2327,6 +2341,9 @@ var SessionStoreInternal = {
+@@ -1554,6 +1584,9 @@ class _SessionStore {
        });
-       this._shouldRestoreLastSession = false;
+       this.#shouldRestoreLastSession = false;
      }
 +    else if (!aInitialState && isRegularWindow) {
 +      lazy.ZenSessionStore.restoreNewWindow(aWindow, this);
 +    }
  
-     if (this._restoreLastWindow && aWindow.toolbar.visible) {
+     if (this.#restoreLastWindow && aWindow.toolbar.visible) {
        // always reset (if not a popup window)
-@@ -2477,7 +2494,7 @@ var SessionStoreInternal = {
+@@ -1704,7 +1737,7 @@ class _SessionStore {
  
      var tabbrowser = aWindow.gBrowser;
  
@@ -119,56 +142,56 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
  
      TAB_EVENTS.forEach(function (aEvent) {
        tabbrowser.tabContainer.removeEventListener(aEvent, this, true);
-@@ -2528,7 +2545,7 @@ var SessionStoreInternal = {
+@@ -1755,7 +1788,7 @@ class _SessionStore {
  
        let isLastRegularWindow =
-         Object.values(this._windows).filter(
+         Object.values(this.#windows).filter(
 -          wData => !wData.isPrivate && !wData.isTaskbarTab
 +          wData => !wData.isPrivate && !wData.isTaskbarTab && !wData.isZenUnsynced
          ).length == 1;
-       this._log.debug(
+       this.#log.debug(
          `onClose, closing window isLastRegularWindow? ${isLastRegularWindow}`
-@@ -2585,8 +2602,8 @@ var SessionStoreInternal = {
+@@ -1812,8 +1845,8 @@ class _SessionStore {
        // 2) Flush the window.
        // 3) When the flush is complete, revisit our decision to store the window
-       //    in _closedWindows, and add/remove as necessary.
+       //    in #closedWindows, and add/remove as necessary.
 -      if (!winData.isPrivate && !winData.isTaskbarTab) {
--        this.maybeSaveClosedWindow(winData, isLastWindow);
+-        this.#maybeSaveClosedWindow(winData, isLastWindow);
 +      if (!winData.isPrivate && !winData.isTaskbarTab && !winData.isZenUnsynced) {
-+        this.maybeSaveClosedWindow(winData, isLastWindow, isLastRegularWindow);
++        this.#maybeSaveClosedWindow(winData, isLastWindow, isLastRegularWindow);
        }
  
        completionPromise = lazy.TabStateFlusher.flushWindow(aWindow).then(() => {
-@@ -2606,8 +2623,9 @@ var SessionStoreInternal = {
+@@ -1833,8 +1866,9 @@ class _SessionStore {
  
          // Save non-private windows if they have at
          // least one saveable tab or are the last window.
 -        if (!winData.isPrivate && !winData.isTaskbarTab) {
--          this.maybeSaveClosedWindow(winData, isLastWindow);
+-          this.#maybeSaveClosedWindow(winData, isLastWindow);
 +        lazy.ZenWindowSync.on_WindowCloseAndBrowserFlushed(browsers);
 +        if (!winData.isPrivate && !winData.isTaskbarTab && !winData.isZenUnsynced) {
-+          this.maybeSaveClosedWindow(winData, isLastWindow, isLastRegularWindow);
++          this.#maybeSaveClosedWindow(winData, isLastWindow, isLastRegularWindow);
  
            if (!isLastWindow && winData.closedId > -1) {
-             this._addClosedAction(
-@@ -2683,7 +2701,7 @@ var SessionStoreInternal = {
+             this.#addClosedAction(
+@@ -1910,7 +1944,7 @@ class _SessionStore {
     *        to call this method again asynchronously (for example, after
     *        a window flush).
     */
--  maybeSaveClosedWindow(winData, isLastWindow) {
-+  maybeSaveClosedWindow(winData, isLastWindow, isLastRegularWindow = false) {
+-  #maybeSaveClosedWindow(winData, isLastWindow) {
++  #maybeSaveClosedWindow(winData, isLastWindow, isLastRegularWindow = false) {
      // Make sure SessionStore is still running, and make sure that we
      // haven't chosen to forget this window.
      if (
-@@ -2700,6 +2718,7 @@ var SessionStoreInternal = {
-       // _closedWindows from a previous call to this function.
-       let winIndex = this._closedWindows.indexOf(winData);
+@@ -1927,6 +1961,7 @@ class _SessionStore {
+       // #closedWindows from a previous call to this function.
+       let winIndex = this.#closedWindows.indexOf(winData);
        let alreadyStored = winIndex != -1;
 +      lazy.ZenSessionStore.maybeSaveClosedWindow(winData, isLastRegularWindow);
        // If sidebar command is truthy, i.e. sidebar is open, store sidebar settings
        let shouldStore = hasSaveableTabs || isLastWindow;
  
-@@ -3522,7 +3541,7 @@ var SessionStoreInternal = {
+@@ -2744,7 +2779,7 @@ class _SessionStore {
      if (!isPrivateWindow && tabState.isPrivate) {
        return;
      }
@@ -177,7 +200,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
        return;
      }
  
-@@ -4260,7 +4279,15 @@ var SessionStoreInternal = {
+@@ -3511,7 +3546,15 @@ class _SessionStore {
          1,
          Math.min(tabState.index, tabState.entries.length)
        );
@@ -194,7 +217,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
  
        if (inBackground === false) {
          aWindow.gBrowser.selectedTab = newTab;
-@@ -4694,6 +4721,8 @@ var SessionStoreInternal = {
+@@ -4036,6 +4079,8 @@ class _SessionStore {
        // Append the tab if we're opening into a different window,
        tabIndex: aSource == aTargetWindow ? pos : Infinity,
        pinned: state.pinned,
@@ -203,7 +226,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
        userContextId: state.userContextId,
        skipLoad: true,
        preferredRemoteType,
-@@ -5191,9 +5220,10 @@ var SessionStoreInternal = {
+@@ -4608,9 +4653,10 @@ class _SessionStore {
        if (activePageData.title && activePageData.title != activePageData.url) {
          win.gBrowser.setInitialTabTitle(tab, activePageData.title, {
            isContentTitle: true,
@@ -215,7 +238,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
        }
      }
  
-@@ -5561,7 +5591,7 @@ var SessionStoreInternal = {
+@@ -4982,7 +5028,7 @@ class _SessionStore {
  
      for (let i = tabbrowser.pinnedTabCount; i < tabbrowser.tabs.length; i++) {
        let tab = tabbrowser.tabs[i];
@@ -224,30 +247,30 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
          removableTabs.push(tab);
        }
      }
-@@ -5674,7 +5704,7 @@ var SessionStoreInternal = {
+@@ -5095,7 +5141,7 @@ class _SessionStore {
  
      // collect the data for all windows
-     for (ix in this._windows) {
--      if (this._windows[ix]._restoring || this._windows[ix].isTaskbarTab) {
-+      if (this._windows[ix]._restoring || this._windows[ix].isTaskbarTab && !this._windows[ix].isZenUnsynced) {
-         // window data is still in _statesToRestore
+     for (ix in this.#windows) {
+-      if (this.#windows[ix]._restoring || this.#windows[ix].isTaskbarTab) {
++      if (this.#windows[ix]._restoring || this.#windows[ix].isTaskbarTab && !this.#windows[ix].isZenUnsynced) {
+         // window data is still in #statesToRestore
          continue;
        }
-@@ -5818,11 +5848,12 @@ var SessionStoreInternal = {
+@@ -5239,11 +5285,12 @@ class _SessionStore {
      }
  
      let tabbrowser = aWindow.gBrowser;
 -    let tabs = tabbrowser.tabs;
 +    let tabs = aWindow.gZenWorkspaces.allStoredTabs;
      /** @type {WindowStateData} */
-     let winData = this._windows[aWindow.__SSi];
+     let winData = this.#windows[aWindow.__SSi];
      let tabsData = (winData.tabs = []);
  
 +    winData.splitViewData = aWindow.gZenViewSplitter?.storeDataForSessionStore();
      // update the internal state data for this window
      for (let tab of tabs) {
        if (tab == aWindow.FirefoxViewHandler.tab) {
-@@ -5833,6 +5864,9 @@ var SessionStoreInternal = {
+@@ -5254,6 +5301,9 @@ class _SessionStore {
        tabsData.push(tabData);
      }
  
@@ -257,7 +280,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
      // update tab group state for this window
      winData.groups = [];
      for (let tabGroup of aWindow.gBrowser.tabGroups) {
-@@ -5849,7 +5883,7 @@ var SessionStoreInternal = {
+@@ -5270,7 +5320,7 @@ class _SessionStore {
      // a window is closed, point to the first item in the tab strip instead (it will never be the Firefox View tab,
      // since it's only inserted into the tab strip after it's selected).
      if (aWindow.FirefoxViewHandler.tab?.selected) {
@@ -266,7 +289,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
        winData.title = tabbrowser.tabs[0].label;
      }
      winData.selected = selectedIndex;
-@@ -6051,8 +6085,8 @@ var SessionStoreInternal = {
+@@ -5472,8 +5522,8 @@ class _SessionStore {
      // selectTab represents.
      let selectTab = 0;
      if (overwriteTabs) {
@@ -277,7 +300,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
        selectTab = Math.min(selectTab, winData.tabs.length);
      }
  
-@@ -6074,6 +6108,7 @@ var SessionStoreInternal = {
+@@ -5495,6 +5545,7 @@ class _SessionStore {
      if (overwriteTabs) {
        for (let i = tabbrowser.browsers.length - 1; i >= 0; i--) {
          if (!tabbrowser.tabs[i].selected) {
@@ -285,7 +308,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
            tabbrowser.removeTab(tabbrowser.tabs[i]);
          }
        }
-@@ -6108,6 +6143,12 @@ var SessionStoreInternal = {
+@@ -5529,6 +5580,12 @@ class _SessionStore {
          savedTabGroup => !openTabGroupIdsInWindow.has(savedTabGroup.id)
        );
      }
@@ -298,7 +321,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
  
      // Move the originally open tabs to the end.
      if (initialTabs) {
-@@ -6674,6 +6715,25 @@ var SessionStoreInternal = {
+@@ -6098,6 +6155,25 @@ class _SessionStore {
  
      // Most of tabData has been restored, now continue with restoring
      // attributes that may trigger external events.
@@ -324,24 +347,25 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
  
      if (tabData.pinned) {
        tabbrowser.pinTab(tab);
-@@ -6859,6 +6919,9 @@ var SessionStoreInternal = {
+@@ -6272,6 +6348,9 @@ class _SessionStore {
          aWindow.gURLBar.readOnly = false;
        }
      }
 +    if (aWinData.isZenUnsynced) {
-+      this._windows[aWindow.__SSi].isZenUnsynced = true;
++      this.#windows[aWindow.__SSi].isZenUnsynced = true;
 +    }
  
      let promiseParts = Promise.withResolvers();
-     aWindow.setTimeout(() => {
-@@ -7356,5 +7419,6 @@ var SessionStoreInternal = {
+     const wasMinimized = aWindow.windowState == aWindow.STATE_MINIMIZED;
+@@ -6774,6 +6853,7 @@ class _SessionStore {
     */
-   _isCmdLineEmpty: function ssi_isCmdLineEmpty(aWindow, aState) {
+   #isCmdLineEmpty(aWindow, aState) {
      var pinnedOnly =
 +      !Services.prefs.getBoolPref("zen.workspaces.continue-where-left-off") &&
        aState.windows &&
        aState.windows.every(win => win.tabs.every(tab => tab.pinned));
-@@ -7654,7 +7718,7 @@ var SessionStoreInternal = {
+ 
+@@ -7116,7 +7196,7 @@ class _SessionStore {
  
        let groupsToSave = new Map();
        for (let tIndex = 0; tIndex < window.tabs.length; ) {
@@ -350,7 +374,7 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
            // Adjust window.selected
            if (tIndex + 1 < window.selected) {
              window.selected -= 1;
-@@ -7669,7 +7733,7 @@ var SessionStoreInternal = {
+@@ -7131,7 +7211,7 @@ class _SessionStore {
            );
            // We don't want to increment tIndex here.
            continue;
@@ -359,15 +383,15 @@ index 76a984f6e21409941ea038218d161e67f2e0c23d..52408568a33a89c0e3d0d1514152ded2
            // Convert any open groups into saved groups.
            let groupStateToSave = window.groups.find(
              groupState => groupState.id == window.tabs[tIndex].groupId
-@@ -8233,7 +8297,6 @@ var SessionStoreInternal = {
+@@ -7691,7 +7771,6 @@ class _SessionStore {
      timer.initWithCallback(
-       function () {
+       () => {
          if (beats <= 0) {
--          this._log.debug(`looseTimer of ${delay} timed out`);
+-          this.#log.debug(`looseTimer of ${delay} timed out`);
            Glean.sessionRestore.shutdownFlushAllOutcomes.timed_out.add(1);
            deferred.resolve();
          }
-@@ -8711,6 +8774,7 @@ var SessionStoreInternal = {
+@@ -8174,6 +8253,7 @@ class _SessionStore {
      if (
        !savedTabGroupState.tabs.length ||
        this.getSavedTabGroup(savedTabGroupState.id)
diff --git a/src/browser/components/sessionstore/TabState-sys-mjs.patch b/src/browser/components/sessionstore/TabState-sys-mjs.patch
index e38734a6b..b0dc28fee 100644
--- a/src/browser/components/sessionstore/TabState-sys-mjs.patch
+++ b/src/browser/components/sessionstore/TabState-sys-mjs.patch
@@ -1,16 +1,16 @@
 diff --git a/browser/components/sessionstore/TabState.sys.mjs b/browser/components/sessionstore/TabState.sys.mjs
-index a33deeb5b587d6a950960a1a4781176e4e730ad7..7927471d389f2626e4cc1b0e7a6eab6446dca432 100644
+index bb7bd8c7ca88f776188fce64e0c85beb5ceb27a5..bdec77ba26172fe1b41369b1d45d5a6f9d52ae25 100644
 --- a/browser/components/sessionstore/TabState.sys.mjs
 +++ b/browser/components/sessionstore/TabState.sys.mjs
-@@ -8,6 +8,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
-   PrivacyFilter: "resource://gre/modules/sessionstore/PrivacyFilter.sys.mjs",
-   TabAttributes: "resource:///modules/sessionstore/TabAttributes.sys.mjs",
-   TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+@@ -10,6 +10,7 @@ const lazy = XPCOMUtils.declareLazy({
+     "moz-src:///browser/components/sessionstore/TabAttributes.sys.mjs",
+   TabStateCache:
+     "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
 +  UrlbarShared: "chrome://browser/content/urlbar/UrlbarShared.mjs",
-   sessionStoreLogger: "resource:///modules/sessionstore/SessionLogger.sys.mjs",
+   sessionStoreLogger:
+     "moz-src:///browser/components/sessionstore/SessionLogger.sys.mjs",
  });
- 
-@@ -103,10 +104,28 @@ class _TabState {
+@@ -106,10 +107,28 @@ class _TabState {
        }
      }
  
@@ -39,7 +39,7 @@ index a33deeb5b587d6a950960a1a4781176e4e730ad7..7927471d389f2626e4cc1b0e7a6eab64
  
      tabData.userContextId = tab.userContextId || 0;
  
-@@ -132,6 +151,10 @@ class _TabState {
+@@ -135,6 +154,10 @@ class _TabState {
        tabData.image = tabbrowser.getIcon(tab);
      }
  
diff --git a/src/browser/components/tabbrowser/Tabbrowser-sys-mjs.patch b/src/browser/components/tabbrowser/Tabbrowser-sys-mjs.patch
new file mode 100644
index 000000000..9ba691bdb
--- /dev/null
+++ b/src/browser/components/tabbrowser/Tabbrowser-sys-mjs.patch
@@ -0,0 +1,1199 @@
+diff --git a/browser/components/tabbrowser/Tabbrowser.sys.mjs b/browser/components/tabbrowser/Tabbrowser.sys.mjs
+index f68e37926001384d0c8e80a3c163dc89e9c4ee5c..aee8241e31fb9a6594dd0b93977226b8b843a8b4 100644
+--- a/browser/components/tabbrowser/Tabbrowser.sys.mjs
++++ b/browser/components/tabbrowser/Tabbrowser.sys.mjs
+@@ -484,6 +484,7 @@ export class Tabbrowser {
+    * @type {MozBrowser[]}
+    */
+   get splitViewBrowsers() {
++    return this.documentGlobal.gZenViewSplitter.splitViewBrowsers;
+     const browsers = [];
+     if (this.#activeSplitView) {
+       for (const tab of this.#activeSplitView.tabs) {
+@@ -582,15 +583,74 @@ export class Tabbrowser {
+     return this.tabContainer.visibleTabs;
+   }
+ 
++  zenHandleTabMove(...args) {
++    return this.#handleTabMove(...args);
++  }
++
++  get zenTabProgressListener() { return TabProgressListener; }
++
++  get TabStateFlusher() {
++    return lazy.TabStateFlusher;
++  }
++
++  get AsyncTabSwitcher() {
++    return lazy.AsyncTabSwitcher;
++  }
++
++  get _numVisiblePinTabsWithoutCollapsed() {
++    let i = 0;
++    for (let item of this.tabContainer.ariaFocusableItems) {
++      if (this.isTabGroupLabel(item) && item.group?.pinned) {
++        i += 1;
++        continue;
++      }
++      if (!item.pinned && !item.hasAttribute("zen-glance-tab")) {
++        break;
++      }
++      if (item.visible) {
++        i += !item.hasAttribute("zen-glance-tab");
++      }
++    }
++    return i;
++  }
++
++  ungroupTabsUntilNoActive(tab) {
++    if (!tab || !tab.group) return;
++    const activeGroups = tab.group.activeGroups;
++    if (activeGroups?.length) {
++      const lastActiveGroup = activeGroups[activeGroups.length - 1];
++      this.#handleTabMove(tab, () => {
++        lastActiveGroup.after(tab);
++      });
++    }
++  }
++
++  get _numZenEssentials() {
++    let i = 0;
++    for (let tab of this.tabs) {
++      if (!tab.hasAttribute("zen-essential") && !tab.hasAttribute("zen-glance-tab")) {
++        break;
++      }
++      i += !tab.hasAttribute("zen-glance-tab");
++    }
++    return i;
++  }
++
+   get pinnedTabCount() {
+-    for (var i = 0; i < this.tabs.length; i++) {
+-      if (!this.tabs[i].pinned) {
++    let i = 0;
++    for (let tab of this.tabs) {
++      if (!tab.pinned && !tab.hasAttribute("zen-glance-tab")) {
+         break;
+       }
++      i += !tab.hasAttribute("zen-glance-tab");
+     }
+     return i;
+   }
+ 
++  get tabsWithoutGlance() {
++    return this.tabs.filter(tab => !tab.hasAttribute("zen-glance-tab"));
++  }
++
+   setSelectedTab(val, metricsContext = null) {
+     if (this.selectedTab === val) {
+       return;
+@@ -603,6 +663,9 @@ export class Tabbrowser {
+     ) {
+       return;
+     }
++    if (this.documentGlobal.gZenWorkspaces.onBeforeTabSelect(val)) {
++      return;
++    }
+     // Update the tab
+     this.tabbox.selectedTab = val;
+ 
+@@ -688,6 +751,10 @@ export class Tabbrowser {
+       userContextId = parseInt(tabArgument.getAttribute("usercontextid"), 10);
+     }
+ 
++    if (typeof this.documentGlobal._zenStartupUnsyncedUserContextId == 'number') {
++      userContextId = this.documentGlobal._zenStartupUnsyncedUserContextId;
++    }
++
+     if (openWindowInfo) {
+       userContextId = openWindowInfo.originAttributes.userContextId;
+     }
+@@ -786,6 +853,8 @@ export class Tabbrowser {
+     this.tabpanels.appendChild(panel);
+ 
+     let tab = this.tabs[0];
++    this.documentGlobal.gZenWorkspaces.handleInitialTab(tab, (!remoteType || remoteType === lazy.E10SUtils.PRIVILEGEDABOUT_REMOTE_TYPE) && !this.documentGlobal.gZenUIManager.testingEnabled);
++    tab._zenContentsVisible = true;
+     tab.linkedPanel = uniqueId;
+     this.#selectedTab = tab;
+     this.#selectedBrowser = browser;
+@@ -1234,18 +1303,24 @@ export class Tabbrowser {
+    *   The context for the operation for telemetry purposes, defaults to an unknown context.
+    */
+   pinTab(aTab, { metricsContext = this.TabMetrics.UNKNOWN_CONTEXT } = {}) {
++    aTab = this.documentGlobal.gZenGlanceManager.getTabOrGlanceParent(aTab);
+     if (aTab.pinned || aTab == this.documentGlobal.FirefoxViewHandler.tab) {
+       return;
+     }
+ 
+     this.showTab(aTab);
++    const handled = this.documentGlobal.gZenFolders.handleTabPin(aTab);
++    if (!handled) {
++      this.ungroupTab(aTab);
+     this.#handleTabMove(aTab, () => {
+       let periphery = this.document.getElementById(
+         "pinned-tabs-container-periphery"
+       );
+       // If periphery is null, append to end
+-      this.pinnedTabsContainer.insertBefore(aTab, periphery);
++      this.tabContainer.tabDragAndDrop.handle_drop_transition(this.tabs[this.pinnedTabCount - 1], aTab, [aTab], false);
++      aTab.hasAttribute("zen-essential") ? this.documentGlobal.gZenWorkspaces.getEssentialsSection(aTab).appendChild(aTab) : this.pinnedTabsContainer.insertBefore(aTab, this.pinnedTabsContainer.lastChild)
+     });
++    }
+ 
+     aTab.setAttribute("pinned", "true");
+     this.#updateTabBarForPinnedTabs();
+@@ -1262,16 +1337,25 @@ export class Tabbrowser {
+    *   The context for the operation for telemetry purposes, defaults to an unknown context.
+    */
+   unpinTab(aTab, { metricsContext = this.TabMetrics.UNKNOWN_CONTEXT } = {}) {
++    aTab = this.documentGlobal.gZenGlanceManager.getTabOrGlanceParent(aTab);
+     if (!aTab.pinned) {
+       return;
+     }
+ 
+     this.#handleTabMove(aTab, () => {
++      const handled = this.documentGlobal.gZenFolders.handleTabUnpin(aTab);
++      if (!handled) {
++        this.tabContainer.tabDragAndDrop.handle_drop_transition(this.tabs[this.pinnedTabCount + 1 /* empty + extra */], aTab, [aTab], true);
++      }
++
+       // we remove this attribute first, so that allTabs represents
+       // the moving of a tab from the pinned tabs container
+       // and back into arrowscrollbox.
+       aTab.removeAttribute("pinned");
+-      this.tabContainer.arrowScrollbox.prepend(aTab);
++      aTab.removeAttribute("zen-essential");
++      if (!handled) {
++        this.documentGlobal.gZenWorkspaces.activeWorkspaceStrip.prepend(aTab);
++      }
+     });
+ 
+     aTab.style.marginInlineStart = "";
+@@ -1494,6 +1578,9 @@ export class Tabbrowser {
+ 
+     let LOCAL_PROTOCOLS = ["chrome:", "about:", "resource:", "data:"];
+ 
++    try {
++      aIconURL = aTab.zenStaticIcon || aIconURL;
++      this.documentGlobal.gZenPinnedTabManager.onTabIconChanged(aTab, aIconURL);
+     if (
+       aIconURL &&
+       !LOCAL_PROTOCOLS.some(protocol => aIconURL.startsWith(protocol))
+@@ -1503,6 +1590,9 @@ export class Tabbrowser {
+       );
+       return;
+     }
++    } catch (e) {
++      console.warn(e);
++    }
+ 
+     let browser = this.getBrowserForTab(aTab);
+     browser.mIconURL = aIconURL;
+@@ -1831,7 +1921,6 @@ export class Tabbrowser {
+ 
+     // Preview mode should not reset the owner
+     if (!this.#previewMode && !oldTab.selected) {
+-      oldTab.owner = null;
+     }
+ 
+     let lastRelatedTab = this.#lastRelatedTabMap.get(oldTab);
+@@ -1922,6 +2011,7 @@ export class Tabbrowser {
+     if (!this.#previewMode) {
+       newTab.recordTimeFromUnloadToReload();
+       newTab.updateLastAccessed();
++      newTab.removeAttribute("unread");
+       oldTab.updateLastAccessed();
+       // if this is the foreground window, update the last-seen timestamps.
+       if (this.documentGlobal == lazy.BrowserWindowTracker.getTopWindow()) {
+@@ -2136,6 +2226,9 @@ export class Tabbrowser {
+     }
+ 
+     let activeEl = this.document.activeElement;
++    if (this.documentGlobal.gURLBar._zenHandleUrlbarClose) {
++      this.documentGlobal.gURLBar._zenHandleUrlbarClose(true);
++    }
+     // If focus is on the old tab, move it to the new tab.
+     if (activeEl == oldTab) {
+       newTab.focus();
+@@ -2174,7 +2267,7 @@ export class Tabbrowser {
+     // Focus the location bar if it was previously focused for that tab.
+     // In full screen mode, only bother making the location bar visible
+     // if the tab is a blank one.
+-    if (this.documentGlobal.gURLBar.getBrowserState(newBrowser).urlbarFocused) {
++    if (this.documentGlobal.gURLBar.getBrowserState(newBrowser).urlbarFocused && (!this.documentGlobal.gZenVerticalTabsManager._hasSetSingleToolbar || this.documentGlobal.isBlankPageURL(newBrowser.currentURI?.spec))) {
+       let selectURL = () => {
+         if (this.#asyncTabSwitching) {
+           // Set _awaitingSetURI flag to suppress popup notification
+@@ -2478,6 +2571,10 @@ export class Tabbrowser {
+     return this.#setTabLabel(aTab, aLabel);
+   }
+ 
++  _setTabLabel(aTab, aLabel, aOptions) {
++    return this.#setTabLabel(aTab, aLabel, aOptions);
++  }
++
+   /**
+    * Sets a tab's label, shortened and clamped for display.
+    *
+@@ -2498,7 +2595,12 @@ export class Tabbrowser {
+    * @returns {boolean}
+    *   Whether the label changed.
+    */
+-  #setTabLabel(aTab, aLabel, { beforeTabOpen, isContentTitle, isURL } = {}) {
++  #setTabLabel(aTab, aLabel, { beforeTabOpen, isContentTitle, isURL, _zenChangeLabelFlag } = {}) {
++    if (!aTab._zenContentsVisible && !aTab._zenChangeLabelFlag && !aTab._labelIsInitialTitle && !this.documentGlobal.gZenWorkspaces.privateWindowOrDisabled && !_zenChangeLabelFlag) {
++      return false;
++    }
++    aLabel = (typeof aTab.zenStaticLabel === "string" && aTab.zenStaticLabel) ? aTab.zenStaticLabel : aLabel;
++    this.documentGlobal.gZenPinnedTabManager.onTabLabelChanged(aTab);
+     if (!aLabel || (isURL && /^about:reader\?url=/.test(aLabel))) {
+       return false;
+     }
+@@ -2657,7 +2759,7 @@ export class Tabbrowser {
+       newIndex = this.selectedTab.index + 1;
+     }
+ 
+-    if (replace) {
++    if (replace && !((targetTab || this.selectedTab)?.hasAttribute('zen-empty-tab'))) {
+       if (this.isTabGroupLabel(targetTab)) {
+         throw new Error(
+           "Replacing a tab group label with a tab is not supported"
+@@ -2971,6 +3073,7 @@ export class Tabbrowser {
+     uriIsAboutBlank,
+     userContextId,
+     skipLoad,
++    _forZenEmptyTab,
+   } = {}) {
+     let b = this.document.createXULElement("browser");
+     // Use the JSM global to create the permanentKey, so that if the
+@@ -3045,10 +3148,7 @@ export class Tabbrowser {
+       b.setAttribute("name", name);
+     }
+ 
+-    if (
+-      lazy.AIWindow.isAIWindowActive(this.documentGlobal) ||
+-      lazy.allowTransparentBrowser
+-    ) {
++    if (lazy.allowTransparentBrowser || _forZenEmptyTab) {
+       b.setAttribute("transparent", "true");
+     }
+ 
+@@ -3212,7 +3312,7 @@ export class Tabbrowser {
+ 
+     let panel = this.getPanel(browser);
+     let uniqueId = this.#generateUniquePanelID();
+-    panel.id = uniqueId;
++    if (!panel.id?.startsWith("zen-")) panel.id = uniqueId;
+     aTab.linkedPanel = uniqueId;
+ 
+     // Inject the <browser> into the DOM if necessary.
+@@ -3269,8 +3369,8 @@ export class Tabbrowser {
+     // If we transitioned from one browser to two browsers, we need to set
+     // hasSiblings=false on both the existing browser and the new browser.
+     if (this.tabs.length == 2) {
+-      this.tabs[0].linkedBrowser.browsingContext.hasSiblings = true;
+-      this.tabs[1].linkedBrowser.browsingContext.hasSiblings = true;
++      if (this.tabs[0].linkedBrowser.browsingContext) this.tabs[0].linkedBrowser.browsingContext.hasSiblings = true;
++      if (this.tabs[1].linkedBrowser.browsingContext) this.tabs[1].linkedBrowser.browsingContext.hasSiblings = true;
+     } else {
+       aTab.linkedBrowser.browsingContext.hasSiblings = this.tabs.length > 1;
+     }
+@@ -3458,7 +3558,6 @@ export class Tabbrowser {
+             {
+               tabIndex: tab.index + 1,
+               userContextId: tab.userContextId,
+-              tabGroup: tab.group,
+               focusUrlBar: true,
+             }
+           );
+@@ -3667,6 +3766,10 @@ export class Tabbrowser {
+       schemelessInput,
+       hasValidUserGestureActivation = false,
+       textDirectiveUserActivation = false,
++      _forZenEmptyTab,
++      essential,
++      zenWorkspaceId,
++      skipRoute = false,
+     } = {}
+   ) {
+     // all callers of addTab that pass a params object need to pass
+@@ -3677,6 +3780,20 @@ export class Tabbrowser {
+       );
+     }
+ 
++    const beforeRouteResult = this.documentGlobal.gZenSpaceRoutingManager.onBeforeAddTab(uriString, { skipRoute, pinned, tabGroup, fromExternal }, this.documentGlobal);
++    if (beforeRouteResult.shouldEarlyExit) {
++      return null;
++    }
++
++    let hasZenDefaultUserContextId = false;
++    let zenForcedWorkspaceId = undefined;
++    if (beforeRouteResult.isRouteFound && (typeof userContextId === "undefined" || fromExternal)) {
++      userContextId = beforeRouteResult.userContextId;
++      hasZenDefaultUserContextId = true;
++    } else if (typeof this.documentGlobal.gZenWorkspaces !== "undefined" && !_forZenEmptyTab) {
++      [userContextId, hasZenDefaultUserContextId, zenForcedWorkspaceId] = this.documentGlobal.gZenWorkspaces.getContextIdIfNeeded(userContextId, fromExternal, triggeringPrincipal);
++    }
++
+     if (!UserInteraction.running("browser.tabs.opening", this.documentGlobal)) {
+       UserInteraction.start(
+         "browser.tabs.opening",
+@@ -3685,6 +3802,7 @@ export class Tabbrowser {
+       );
+     }
+ 
++    if (!this.documentGlobal.gURLBar.hasAttribute("zen-newtab")) {
+     // If we're opening a foreground tab, set the owner by default.
+     ownerTab ??= inBackground ? null : this.selectedTab;
+ 
+@@ -3692,6 +3810,7 @@ export class Tabbrowser {
+     if (this.selectedTab.owner) {
+       this.selectedTab.owner = null;
+     }
++    }
+ 
+     // Find the tab that opened this one, if any. This is used for
+     // determining positioning, and inherited attributes such as the
+@@ -3744,6 +3863,22 @@ export class Tabbrowser {
+         noInitialLabel,
+         skipBackgroundNotify,
+       });
++      if (hasZenDefaultUserContextId) {
++        t.setAttribute("zenDefaultUserContextId", "true");
++      }
++      if (zenWorkspaceId) {
++        t.setAttribute("zen-workspace-id", zenWorkspaceId);
++        t.setAttribute("change-workspace", "")
++      } else if (zenForcedWorkspaceId !== undefined) {
++        t.setAttribute("zen-workspace-id", zenForcedWorkspaceId);
++        t.setAttribute("change-workspace", "")
++      }
++      if (_forZenEmptyTab) {
++        t.setAttribute("zen-empty-tab", "true");
++      }
++      if (essential) {
++        t.setAttribute("zen-essential", "true");
++      }
+       if (insertTab) {
+         // Insert the tab into the tab container in the correct position.
+         this.#insertTabAtIndex(t, {
+@@ -3752,6 +3887,7 @@ export class Tabbrowser {
+           ownerTab,
+           openerTab,
+           pinned,
++          essential,
+           bulkOrderedOpen,
+           tabGroup: tabGroup ?? openerTab?.group,
+         });
+@@ -3770,6 +3906,7 @@ export class Tabbrowser {
+         openWindowInfo,
+         skipLoad,
+         triggeringRemoteType,
++        _forZenEmptyTab,
+       }));
+ 
+       if (focusUrlBar) {
+@@ -3894,6 +4031,12 @@ export class Tabbrowser {
+       }
+     }
+ 
++    if (typeof this.documentGlobal.gZenVerticalTabsManager !== "undefined") {
++      this.documentGlobal.gZenVerticalTabsManager.animateItemOpen(t);
++    }
++    if (typeof this.documentGlobal.gZenCompactModeManager !== "undefined" && !skipLoad && insertTab) {
++      this.documentGlobal.gZenCompactModeManager._onTabOpen(t, inBackground, beforeRouteResult);
++    }
+     // Additionally send pinned tab events
+     if (pinned) {
+       this.#notifyPinnedStatus(t);
+@@ -3904,6 +4047,15 @@ export class Tabbrowser {
+     if (!inBackground) {
+       this.selectedTab = t;
+     }
++
++    this.documentGlobal.gZenSpaceRoutingManager.onAfterAddTab(
++      uriString,
++      t,
++      { skipRoute: skipRoute || _forZenEmptyTab, fromExternal, pinned, tabGroup, inBackground },
++      this.documentGlobal,
++      beforeRouteResult,
++    );
++
+     return t;
+   }
+ 
+@@ -4125,6 +4277,7 @@ export class Tabbrowser {
+       insertBefore = null,
+       isAdoptingGroup = false,
+       metricsContext = this.TabMetrics.UNKNOWN_CONTEXT,
++      forSplitView = false,
+     } = {}
+   ) {
+     if (
+@@ -4135,7 +4288,6 @@ export class Tabbrowser {
+           !this.isSplitViewWrapper(tabOrSplitView)
+       )
+     ) {
+-      throw new Error("Cannot create tab group with zero tabs or split views");
+     }
+ 
+     if (!color) {
+@@ -4150,7 +4302,15 @@ export class Tabbrowser {
+       id = `${Date.now()}-${Math.round(Math.random() * 100)}`;
+     }
+     let group = this.#createTabGroup(id, color, false, label, isAdoptingGroup);
+-    this.tabContainer.insertBefore(group, insertBefore?.group ?? insertBefore);
++    if (forSplitView) {
++      group.setAttribute('split-view-group', true);
++    }
++    group.essential = tabsAndSplitViews.some(tab => tab.hasAttribute("essential"));
++    group.pinned = group.essential || tabsAndSplitViews.some(tab => tab.pinned);
++    if (forSplitView && !insertBefore?.group?.isZenFolder) insertBefore = insertBefore?.group ?? insertBefore;
++    insertBefore.before(
++      group,
++    );
+     group.addTabs(tabsAndSplitViews, metricsContext);
+ 
+     // Bail out if the group is empty at this point. This can happen if all
+@@ -4253,7 +4413,7 @@ export class Tabbrowser {
+     }
+ 
+     this.#handleTabMove(tab, () =>
+-      this.tabContainer.insertBefore(tab, tab.group.nextElementSibling)
++      tab.group.after(tab)
+     );
+   }
+ 
+@@ -4337,6 +4497,7 @@ export class Tabbrowser {
+       color: group.color,
+       insertBefore: newTabs[0],
+       isAdoptingGroup: true,
++      forSplitView: group.hasAttribute('split-view-group'),
+     });
+   }
+ 
+@@ -4597,6 +4758,7 @@ export class Tabbrowser {
+       openWindowInfo,
+       skipLoad,
+       triggeringRemoteType,
++      _forZenEmptyTab
+     }
+   ) {
+     // If we don't have a preferred remote type (or it is `NOT_REMOTE`), and
+@@ -4660,6 +4822,7 @@ export class Tabbrowser {
+         openWindowInfo,
+         name,
+         skipLoad,
++        _forZenEmptyTab
+       });
+     }
+ 
+@@ -4943,8 +5106,9 @@ export class Tabbrowser {
+       }
+ 
+       // Add a new tab if needed.
+-      if (!tab) {
+-        let createLazyBrowser = restoreTabsLazily && !select && !tabData.pinned;
++      if (!tab || tab?._markedForReplacement) {
++        let createLazyBrowser =
++          restoreTabsLazily && !(tabData.pinned && !Services.prefs.getBoolPref("browser.sessionstore.restore_pinned_tabs_on_demand"));
+ 
+         let url = "about:blank";
+         if (tabData.entries?.length) {
+@@ -4977,8 +5141,10 @@ export class Tabbrowser {
+           insertTab: false,
+           skipLoad: true,
+           preferredRemoteType,
++          _forZenEmptyTab: tabData.zenIsEmpty,
+         });
+-
++        tab._originalUrl = url;
++        this.documentGlobal.gZenSessionStore.restoreInitialTabData(tab, tabData);
+         if (select) {
+           tabToSelect = tab;
+         }
+@@ -5000,7 +5166,8 @@ export class Tabbrowser {
+         this.pinTab(tab);
+         // Then ensure all the tab open/pinning information is sent.
+         this.#fireTabOpen(tab, {});
+-      } else if (tabData.groupId) {
++      }
++      if (tabData.groupId && tabGroupWorkingData.get(tabData.groupId)) {
+         let { groupId } = tabData;
+         const tabGroup = tabGroupWorkingData.get(groupId);
+         // if a tab refers to a tab group we don't know, skip any group
+@@ -5020,7 +5187,10 @@ export class Tabbrowser {
+               tabGroup.stateData.id,
+               tabGroup.stateData.color,
+               tabGroup.stateData.collapsed,
+-              tabGroup.stateData.name
++              tabGroup.stateData.name,
++              tabGroup.stateData.pinned,
++              tabGroup.stateData.essential,
++              tabGroup.stateData.splitView,
+             );
+             tabsFragment.appendChild(tabGroup.node);
+           }
+@@ -5080,9 +5250,21 @@ export class Tabbrowser {
+     // to remove the old selected tab.
+     if (tabToSelect) {
+       let leftoverTab = this.selectedTab;
++      if (this._hasAlreadyInitializedZenSessionStore || !this.documentGlobal.gZenWorkspaces.workspaceEnabled) {
+       this.selectedTab = tabToSelect;
+       this.removeTab(leftoverTab);
++      } else {
++        this.documentGlobal.gZenWorkspaces._tabToRemoveForEmpty = leftoverTab;
++        if (Services.prefs.getBoolPref("zen.workspaces.continue-where-left-off")) {
++          this.documentGlobal.gZenWorkspaces._tabToSelect = selectTab - 1; // -1 for the empty tab.
++        }
++        if (this.documentGlobal.gZenWorkspaces._initialTab && !this.documentGlobal.gZenVerticalTabsManager._canReplaceNewTab) {
++          this.documentGlobal.gZenWorkspaces._initialTab._shouldRemove = true;
++        }
++      }
+     }
++    delete this.documentGlobal.__isNewZenWindow;
++    this._hasAlreadyInitializedZenSessionStore = true;
+ 
+     if (tabs.length > 1 || !tabs[0].selected) {
+       this.#updateTabsAfterInsert();
+@@ -5313,11 +5495,17 @@ export class Tabbrowser {
+     if (ownerTab) {
+       tab.owner = ownerTab;
+     }
++    if ((!tab.pinned && tabGroup?.isZenFolder && !Services.prefs.getBoolPref('zen.folders.owned-tabs-in-folder')) || (tabGroup && tabGroup.hasAttribute("split-view-group"))) {
++      tabGroup = null;
++    }
++    if (openerTab?.hasAttribute("zen-glance-tab")) {
++      openerTab = this.documentGlobal.gZenGlanceManager.getTabOrGlanceParent(openerTab);
++    }
+ 
+     // Ensure we have an index if one was not provided.
+     if (typeof elementIndex != "number" && typeof tabIndex != "number") {
+       // Move the new tab after another tab if needed, to the end otherwise.
+-      elementIndex = Infinity;
++      elementIndex = Services.prefs.getBoolPref("zen.view.show-newtab-button-top") ? this._numVisiblePinTabsWithoutCollapsed : Infinity;
+       let insertRelatedAfterCurrent = Services.prefs.getBoolPref(
+         "browser.tabs.insertRelatedAfterCurrent"
+       );
+@@ -5332,7 +5520,7 @@ export class Tabbrowser {
+           (insertRelatedAfterCurrent && lastRelatedTab) ||
+           openerTab ||
+           this.selectedTab;
+-        if (!tabGroup) {
++        if (!tabGroup && pinned === previousTab.group?.pinned) {
+           tabGroup = previousTab.group;
+         }
+         if (
+@@ -5348,7 +5536,7 @@ export class Tabbrowser {
+               previousTab.splitview
+             ) + 1;
+         } else if (previousTab.visible) {
+-          elementIndex = previousTab.elementIndex + 1;
++          elementIndex = (typeof previousTab.elementIndex === 'undefined') ? elementIndex : (previousTab.elementIndex + 1);
+         } else if (previousTab == this.documentGlobal.FirefoxViewHandler.tab) {
+           elementIndex = 0;
+         }
+@@ -5376,14 +5564,14 @@ export class Tabbrowser {
+     }
+     // Ensure index is within bounds.
+     if (tab.pinned) {
+-      index = Math.max(index, 0);
+-      index = Math.min(index, this.pinnedTabCount);
++      index = Math.max(index, tab.hasAttribute("zen-essential") ? 0 : this._numZenEssentials);
++      index = Math.min(index, tab.hasAttribute("zen-essential") ? this._numZenEssentials : this._numVisiblePinTabsWithoutCollapsed);
+     } else {
+-      index = Math.max(index, this.pinnedTabCount);
++      index = Math.max(index, typeof elementIndex == "number" ? this._numVisiblePinTabsWithoutCollapsed : this.pinnedTabCount);
+       index = Math.min(index, allItems.length);
+     }
+     /** @type {MozTabbrowserTab|undefined} */
+-    let itemAfter = allItems.at(index);
++    let itemAfter = this.documentGlobal.gZenGlanceManager.getTabOrGlanceParent(allItems.at(index));
+ 
+     if (pinned && !itemAfter?.pinned) {
+       itemAfter = null;
+@@ -5400,7 +5588,7 @@ export class Tabbrowser {
+ 
+     this.tabContainer._invalidateCachedTabs();
+ 
+-    if (tabGroup) {
++    if (tabGroup && !tabGroup.hasAttribute("split-view-group")) {
+       if (
+         (this.isTab(itemAfter) && itemAfter.group == tabGroup) ||
+         this.isSplitViewWrapper(itemAfter)
+@@ -5431,7 +5619,11 @@ export class Tabbrowser {
+       const tabContainer = pinned
+         ? this.tabContainer.pinnedTabsContainer
+         : this.tabContainer;
++      if (itemAfter) {
++        itemAfter.before(tab);
++      } else {
+       tabContainer.insertBefore(tab, itemAfter);
++      }
+     }
+ 
+     if (tab.group?.collapsed) {
+@@ -5446,6 +5638,7 @@ export class Tabbrowser {
+     if (pinned) {
+       this.#updateTabBarForPinnedTabs();
+     }
++    this.documentGlobal.gZenWorkspaces.fixTabInsertLocation(tab, itemAfter);
+ 
+     this.documentGlobal.TabBarVisibility.update();
+   }
+@@ -6025,6 +6218,7 @@ export class Tabbrowser {
+       metricsContext,
+     } = {}
+   ) {
++    tabs = tabs.filter(tab => !tab.hasAttribute("zen-empty-tab"));
+     // When 'closeWindowWithLastTab' pref is enabled, closing all tabs
+     // can be considered equivalent to closing the window.
+     if (
+@@ -6135,6 +6329,7 @@ export class Tabbrowser {
+           closedTabCount -= 1;
+         }
+       }
++      this.documentGlobal.gZenUIManager.onTabClose(undefined);
+ 
+       if (closedTabCount > 0) {
+         this.recordTabMetrics(
+@@ -6236,6 +6431,14 @@ export class Tabbrowser {
+       return;
+     }
+ 
++    if (this.documentGlobal.gZenWorkspaces.workspaceEnabled) {
++      let newTab = this.documentGlobal.gZenWorkspaces.handleTabBeforeClose(aTab, closeWindowWithLastTab);
++      if (newTab) {
++        this.selectedTab = newTab;
++      }
++    }
++    animate &&= !aTab.group?.hasAttribute("split-view-group");
++
+     let isVisibleTab = aTab.visible;
+     // We have to sample the tab width now, since #beginRemoveTab might
+     // end up modifying the DOM in such a way that aTab gets a new
+@@ -6244,6 +6447,9 @@ export class Tabbrowser {
+     let tabWidth =
+       this.documentGlobal.windowUtils.getBoundsWithoutFlushing(aTab).width;
+     let isLastTab = this.#isLastTabInWindow(aTab);
++    if (this.documentGlobal.gZenGlanceManager.manageTabClose(aTab)) {
++      return;
++    }
+     if (
+       !this.#beginRemoveTab(aTab, {
+         closeWindowFastpath: true,
+@@ -6254,13 +6460,14 @@ export class Tabbrowser {
+         metricsContext,
+       })
+     ) {
++      delete this.documentGlobal.gZenWorkspaces._isClosingWindow;
+       Glean.browserTabclose.timeAnim.cancel(aTab._closeTimeAnimTimerId);
+       aTab._closeTimeAnimTimerId = null;
+       Glean.browserTabclose.timeNoAnim.cancel(aTab._closeTimeNoAnimTimerId);
+       aTab._closeTimeNoAnimTimerId = null;
+       return;
+     }
+-
++    this.documentGlobal.gZenWorkspaces.handleTabBeforeRemove();
+     let lockTabSizing =
+       !this.tabContainer.verticalMode &&
+       !aTab.pinned &&
+@@ -6291,7 +6498,13 @@ export class Tabbrowser {
+       // We're not animating, so we can cancel the animation stopwatch.
+       Glean.browserTabclose.timeAnim.cancel(aTab._closeTimeAnimTimerId);
+       aTab._closeTimeAnimTimerId = null;
+-      this._endRemoveTab(aTab);
++      if (animate && !this.documentGlobal.gReduceMotion && !(this.documentGlobal.gZenUIManager.testingEnabled && !this.documentGlobal.gZenUIManager.profilingEnabled)) {
++        this.documentGlobal.gZenVerticalTabsManager.animateItemClose(aTab, (animate && !this.documentGlobal.gReduceMotion)).then(() => {
++          this._endRemoveTab(aTab);
++        });
++      } else {
++        this._endRemoveTab(aTab);
++      }
+       return;
+     }
+ 
+@@ -6331,7 +6544,9 @@ export class Tabbrowser {
+   get #shouldCloseWindowWithLastTab() {
+     return (
+       !this.documentGlobal.toolbar.visible ||
+-      Services.prefs.getBoolPref("browser.tabs.closeWindowWithLastTab")
++      (Services.prefs.getBoolPref("browser.tabs.closeWindowWithLastTab") &&
++        !this.documentGlobal.gZenWorkspaces._isClosingWindow &&
++        !this.documentGlobal.gZenWorkspaces._removedByStartupPage)
+     );
+   }
+ 
+@@ -6347,7 +6562,7 @@ export class Tabbrowser {
+    */
+   #isLastTabInWindow(tab) {
+     for (const otherTab of this.tabs) {
+-      if (otherTab != tab && otherTab.isOpen && !otherTab.hidden) {
++      if (otherTab != tab && otherTab.isOpen && !otherTab.hidden && !otherTab.hasAttribute("zen-empty-tab")) {
+         return false;
+       }
+     }
+@@ -6488,6 +6703,7 @@ export class Tabbrowser {
+ 
+       newTab = true;
+     }
++    this.documentGlobal.gZenWorkspaces._removedByStartupPage = false;
+     aTab._endRemoveArgs = [closeWindow, newTab];
+ 
+     // swapBrowsersAndCloseOther will take care of closing the window without animation.
+@@ -6542,13 +6758,7 @@ export class Tabbrowser {
+     }
+ 
+     if (newTab) {
+-      this.addTrustedTab(this.documentGlobal.BROWSER_NEW_TAB_URL, {
+-        skipAnimation: true,
+-        // In the event that insertAfterCurrent is set and the current tab is
+-        // inside a group that is being closed we want to avoid creating the
+-        // new tab inside that group.
+-        tabIndex: 0,
+-      });
++      this.documentGlobal.gZenWorkspaces.selectEmptyTab(this.documentGlobal.BROWSER_NEW_TAB_URL);
+     } else {
+       this.documentGlobal.TabBarVisibility.update();
+     }
+@@ -6701,6 +6911,7 @@ export class Tabbrowser {
+       this.tabs[i]._index = i;
+     }
+ 
++    this.documentGlobal.gZenWorkspaces.updateTabsContainers();
+     if (!this.#windowIsClosing) {
+       // update tab close buttons state
+       this.tabContainer._updateCloseButtons();
+@@ -6891,6 +7102,7 @@ export class Tabbrowser {
+       memory_after: await getTotalMemoryUsage(),
+       time_to_unload_in_ms: timeElapsed,
+     });
++    return true;
+   }
+ 
+   /**
+@@ -6937,11 +7149,12 @@ export class Tabbrowser {
+     }
+ 
+     let excludeTabs = new Set(aExcludeTabs);
++    this.documentGlobal.gZenWorkspaces.getTabsToExclude(aTab).forEach(tab => excludeTabs.add(tab));
+ 
+     // If this tab has a successor, it should be selectable, since
+     // hiding or closing a tab removes that tab as a successor.
+     if (aTab.successor && !excludeTabs.has(aTab.successor)) {
+-      return aTab.successor;
++      return this.documentGlobal.gZenWorkspaces.findTabToBlur(aTab.successor);
+     }
+ 
+     if (
+@@ -6949,13 +7162,13 @@ export class Tabbrowser {
+       !excludeTabs.has(aTab.owner) &&
+       Services.prefs.getBoolPref("browser.tabs.selectOwnerOnClose")
+     ) {
+-      return aTab.owner;
++      return this.documentGlobal.gZenWorkspaces.findTabToBlur(aTab.owner);
+     }
+ 
+     // Try to find a remaining tab that comes after the given tab
+     let remainingTabs = Array.prototype.filter.call(
+       this.visibleTabs,
+-      tab => !excludeTabs.has(tab)
++      tab => !excludeTabs.has(tab) && this.documentGlobal.gZenWorkspaces._shouldChangeToTab(tab) && tab !== aTab
+     );
+ 
+     if (Services.prefs.getBoolPref("browser.tabs.selectMRUOnClose", false)) {
+@@ -6970,6 +7183,13 @@ export class Tabbrowser {
+       }
+     }
+ 
++    if (remainingTabs.length > 0 && Services.prefs.getBoolPref("zen.tabs.select-recently-used-on-close")) {
++      let mostRecentTab = remainingTabs.reduce((a, b) =>
++        b.lastAccessed > a.lastAccessed ? b : a
++      );
++      return this.documentGlobal.gZenWorkspaces.findTabToBlur(mostRecentTab);
++    }
++
+     let tab = this.tabContainer.findNextTab(aTab, {
+       direction: 1,
+       filter: _tab => remainingTabs.includes(_tab),
+@@ -6983,7 +7203,7 @@ export class Tabbrowser {
+     }
+ 
+     if (tab) {
+-      return tab;
++      return this.documentGlobal.gZenWorkspaces.findTabToBlur(tab);
+     }
+ 
+     // If no qualifying visible tab was found, see if there is a tab in
+@@ -7004,7 +7224,7 @@ export class Tabbrowser {
+       });
+     }
+ 
+-    return tab;
++    return this.documentGlobal.gZenWorkspaces.findTabToBlur(tab);
+   }
+ 
+   #blurTab(aTab) {
+@@ -7021,7 +7241,7 @@ export class Tabbrowser {
+    * @returns {boolean}
+    *   False if swapping isn't permitted, true otherwise.
+    */
+-  swapBrowsersAndCloseOther(aOurTab, aOtherTab) {
++  swapBrowsersAndCloseOther(aOurTab, aOtherTab, zenCloseOther = true) {
+     // Do not allow transfering a private tab to a non-private window
+     // and vice versa.
+     if (
+@@ -7080,6 +7300,7 @@ export class Tabbrowser {
+     // fire the beforeunload event in the process.  Close the other
+     // window if this was its last tab.
+     if (
++      zenCloseOther &&
+       !remoteBrowser.#beginRemoveTab(aOtherTab, {
+         adoptedByTab: aOurTab,
+         closeWindowWithLastTab: true,
+@@ -7091,7 +7312,7 @@ export class Tabbrowser {
+     // If this is the last tab of the window, hide the window
+     // immediately without animation before the docshell swap, to avoid
+     // about:blank being painted.
+-    let [closeWindow] = aOtherTab._endRemoveArgs;
++    let [closeWindow] = !zenCloseOther ? [false] : aOtherTab._endRemoveArgs;
+     if (closeWindow) {
+       let win = aOtherTab.documentGlobal;
+       win.windowUtils.suppressAnimation(true);
+@@ -7231,11 +7452,13 @@ export class Tabbrowser {
+     }
+ 
+     // Finish tearing down the tab that's going away.
++    if (zenCloseOther) {
+     if (closeWindow) {
+       aOtherTab.documentGlobal.close();
+     } else {
+       remoteBrowser._endRemoveTab(aOtherTab);
+     }
++    }
+ 
+     this.setTabTitle(aOurTab);
+ 
+@@ -7484,10 +7707,10 @@ export class Tabbrowser {
+     }
+   }
+ 
+-  hideTab(aTab, aSource) {
++  hideTab(aTab, aSource, forZenWorkspaces = false) {
+     if (
+       aTab.hidden ||
+-      aTab.pinned ||
++      (aTab.pinned && !forZenWorkspaces) ||
+       aTab.selected ||
+       aTab.closing ||
+       // Tabs that are sharing the screen, microphone or camera cannot be hidden.
+@@ -7576,7 +7799,8 @@ export class Tabbrowser {
+    * @param {object} [aOptions={}]
+    *   Key-value pairs that will be serialized into the features string.
+    */
+-  replaceTabWithWindow(aTab, aOptions = {}) {
++  replaceTabWithWindow(aTab, aOptions = {}, zenForceSync = false) {
++    if (!this.isTab(aTab)) return; // TODO: Handle tab groups
+     if (this.tabs.length == 1) {
+       return null;
+     }
+@@ -7593,7 +7817,7 @@ export class Tabbrowser {
+     // tell a new window to take the "dropped" tab
+     let args = Cc["@mozilla.org/array;1"].createInstance(Ci.nsIMutableArray);
+     args.appendElement(aTab.splitview ?? aTab);
+-    return lazy.BrowserWindowTracker.openWindow({
++    let win = lazy.BrowserWindowTracker.openWindow({
+       private: lazy.PrivateBrowsingUtils.isWindowPrivate(this.documentGlobal),
+       features: Object.entries(aOptions)
+         .map(([key, value]) => `${key}=${value}`)
+@@ -7601,6 +7825,8 @@ export class Tabbrowser {
+       openerWindow: this.documentGlobal,
+       args,
+     });
++    win._zenStartupSyncFlag = (zenForceSync || !Services.prefs.getBoolPref("zen.tabs.dnd-open-blank-window", true)) ? 'synced' : 'unsynced';
++    return win;
+   }
+ 
+   /**
+@@ -7734,7 +7960,7 @@ export class Tabbrowser {
+    * @returns {element is MozTabbrowserTabGroup}
+    */
+   isTabGroup(element) {
+-    return !!(element?.tagName == "tab-group");
++    return !!(element?.tagName == "tab-group" || element?.tagName == "zen-folder");
+   }
+ 
+   /**
+@@ -7807,8 +8033,8 @@ export class Tabbrowser {
+     }
+ 
+     // Don't allow mixing pinned and unpinned tabs.
+-    if (this.isTab(element) && element.pinned) {
+-      tabIndex = Math.min(tabIndex, this.pinnedTabCount - 1);
++    if (element.pinned) {
++      tabIndex = element.hasAttribute('zen-essential') ? Math.min(tabIndex, this._numZenEssentials - 1) : Math.min(Math.max(tabIndex, this._numZenEssentials), this.pinnedTabCount - 1);
+     } else {
+       tabIndex = Math.max(tabIndex, this.pinnedTabCount);
+     }
+@@ -7854,8 +8080,8 @@ export class Tabbrowser {
+     this.#handleTabMove(
+       element,
+       () => {
+-        let neighbor = this.tabs[tabIndex];
+-        if (forceUngrouped && neighbor?.group) {
++        let neighbor = this.documentGlobal.gZenGlanceManager.getTabOrGlanceParent(this.tabs[tabIndex]);
++        if ((forceUngrouped && neighbor?.group) || neighbor?.group?.hasAttribute("split-view-group")) {
+           neighbor = neighbor.group;
+         }
+         if (neighbor?.splitview) {
+@@ -7866,6 +8092,12 @@ export class Tabbrowser {
+             return;
+           }
+         }
++        if (element.group?.hasAttribute("split-view-group")) {
++          element = element.group;
++        }
++        if (element.group?.hasAttribute("split-view-group") && neighbor == element.group) {
++          return;
++        }
+ 
+         if (movingForwards && neighbor) {
+           neighbor.after(element);
+@@ -7939,23 +8171,31 @@ export class Tabbrowser {
+   ) {
+     if (this.isTabGroupLabel(targetElement)) {
+       targetElement = targetElement.group;
+-      if (!moveBefore && !targetElement.collapsed) {
++      if (!moveBefore && !targetElement.collapsed && !targetElement.hasAttribute("split-view-group")) {
+         // Right after the tab group label = before the first tab in the tab group
+         targetElement = targetElement.tabs[0];
+         moveBefore = true;
+       }
+     }
+-    if (this.isTabGroupLabel(element)) {
++    if (this.isTabGroupLabel(element) || element.group?.hasAttribute("split-view-group")) {
+       element = element.group;
+-      if (targetElement?.group) {
+-        targetElement = targetElement.group;
+-      }
+     }
+ 
+     // Don't allow mixing pinned and unpinned tabs.
++    targetElement = this.documentGlobal.gZenGlanceManager.getTabOrGlanceParent(targetElement);
++    if (targetElement?.classList.contains('tab-group-label-container')) {
++      targetElement = targetElement.parentElement;
++    }
++    if (element.hasAttribute('zen-essential') && !targetElement?.hasAttribute('zen-essential')) {
++      targetElement = this.tabsWithoutGlance[this._numZenEssentials - 1];
++    } else
+     if (element.pinned && !targetElement?.pinned) {
+-      targetElement = this.tabs[this.pinnedTabCount - 1];
++      targetElement = this.tabsWithoutGlance[this.pinnedTabCount - 1];
+       moveBefore = false;
++      if (!this.visibleTabs.includes(targetElement)) {
++        targetElement = this.documentGlobal.gZenWorkspaces.pinnedTabsContainer.querySelector('.pinned-tabs-container-separator')
++        moveBefore = true;
++      }
+     } else if (!element.pinned && targetElement && targetElement.pinned) {
+       // If the caller asks to move an unpinned element next to a pinned
+       // tab, move the unpinned element to be the first unpinned element
+@@ -7968,12 +8208,35 @@ export class Tabbrowser {
+       //    move the tab group right before the first unpinned tab.
+       // 4. Moving a tab group and the first unpinned tab is grouped:
+       //    move the tab group right before the first unpinned tab's tab group.
+-      targetElement = this.tabs[this.pinnedTabCount];
++      targetElement = this.tabsWithoutGlance[this.pinnedTabCount];
+       if (targetElement.group) {
+         targetElement = targetElement.group;
+       }
+       moveBefore = true;
+     }
++    if (!this.documentGlobal.gZenFolders.canDropElement(element, targetElement)) {
++      element = element.group;
++    }
++    if (!element.hasAttribute('zen-essential') && targetElement?.hasAttribute('zen-essential')) {
++      targetElement = null;
++      moveBefore = false;
++    }
++    // It is necessary to place the check below to avoid inserting an element
++    // inside when the split group is the last element.
++    if (targetElement?.group?.hasAttribute("split-view-group")) {
++      targetElement = targetElement.group;
++    }
++    if (targetElement?.hasAttribute("zen-empty-tab")) {
++      // When the folder is the last element in the pinned section,
++      // targetElement is a tab with the zen-empty-tab attribute.
++      // If the movement is from top to bottom, it must be redefined as a folder.
++      if (!moveBefore) {
++        targetElement = targetElement.group;
++      } else {
++        // Always insert an element after zen-empty-tab to avoid it moving from the first position
++        moveBefore = false;
++      }
++    }
+ 
+     // We want to include the splitview wrapper if it's the targetElement, but
+     // not in the case where we want to reverse tabs within the same splitview.
+@@ -7982,6 +8245,7 @@ export class Tabbrowser {
+     }
+ 
+     let getContainer = () =>
++      element.hasAttribute("zen-essential") ? this.documentGlobal.gZenWorkspaces.getEssentialsSection(element) :
+       element.pinned
+         ? this.tabContainer.pinnedTabsContainer
+         : this.tabContainer;
+@@ -7990,11 +8254,15 @@ export class Tabbrowser {
+       element,
+       () => {
+         if (moveBefore) {
+-          getContainer().insertBefore(element, targetElement);
++          targetElement.parentElement.insertBefore(element, targetElement);
+         } else if (targetElement) {
+           targetElement.after(element);
+         } else {
++          if (element.pinned) {
++            getContainer().prepend(element);
++          } else {
+           getContainer().appendChild(element);
++          }
+         }
+       },
+       { metricsContext }
+@@ -8070,11 +8338,15 @@ export class Tabbrowser {
+    *   The context for the operation for telemetry purposes.
+    */
+   moveTabToExistingGroup(aTab, aGroup, { metricsContext } = {}) {
+-    if (!this.isTab(aTab)) {
++    if (!this.isTab(aTab) && !aTab.hasAttribute('split-view-group')) {
+       throw new Error("Can only move a tab into a tab group");
+     }
+-    if (aTab.pinned) {
+-      return;
++    if (aTab.pinned != !!aGroup.pinned) {
++      if (aGroup.pinned) {
++        this.pinTab(aTab);
++      } else {
++        this.unpinTab(aTab);
++      }
+     }
+     if (aTab.group && aTab.group.id === aGroup.id) {
+       return;
+@@ -8153,6 +8425,7 @@ export class Tabbrowser {
+ 
+     let state = {
+       tabIndex: tab.index,
++      workspaceId: tab.getAttribute("zen-workspace-id")
+     };
+     if (tab.visible) {
+       state.elementIndex = tab.elementIndex;
+@@ -8190,7 +8463,7 @@ export class Tabbrowser {
+     let changedSplitView =
+       previousTabState.splitViewId != currentTabState.splitViewId;
+ 
+-    if (changedPosition || changedTabGroup || changedSplitView) {
++    if (changedPosition || changedTabGroup || changedSplitView || (previousTabState.workspaceId != currentTabState.workspaceId)) {
+       tab.dispatchEvent(
+         new this.documentGlobal.CustomEvent("TabMove", {
+           bubbles: true,
+@@ -8248,6 +8521,10 @@ export class Tabbrowser {
+ 
+     moveActionCallback();
+ 
++    this.documentGlobal.gZenWorkspaces.makeSureEmptyTabIsFirst();
++    this.documentGlobal.gZenViewSplitter._maybeRemoveFakeBrowser(false);
++    this.documentGlobal.gZenViewSplitter._canDrop = false;
++
+     // Clear tabs cache after moving nodes because the order of tabs may have
+     // changed.
+     this.tabContainer._invalidateCachedTabs();
+@@ -8307,7 +8584,22 @@ export class Tabbrowser {
+    * @returns {object}
+    *    The new tab in the current window, null if the tab couldn't be adopted.
+    */
+-  adoptTab(aTab, { elementIndex, tabIndex, selectTab = false } = {}) {
++  adoptTab(aTab, { elementIndex, tabIndex, selectTab = false, spaceId = null } = {}) {
++    if (this.documentGlobal.gZenWorkspaces.currentWindowIsSyncing && aTab.documentGlobal.gZenWorkspaces?.currentWindowIsSyncing) {
++      const tabId = aTab.id;
++      const thisTab = this.documentGlobal.gZenWindowSync.getItemFromWindow(this.documentGlobal, tabId);
++      if (thisTab) {
++        // Just move the tab to the index
++        this.moveTabTo(thisTab, { elementIndex, tabIndex });
++        if (spaceId) {
++          thisTab.setAttribute("zen-workspace-id", spaceId);
++        }
++        if (selectTab) {
++          this.selectedTab = thisTab;
++        }
++        return thisTab;
++      }
++    }
+     // Swap the dropped tab with a new one we create and then close
+     // it in the other window (making it seem to have moved between
+     // windows). We also ensure that the tab we create to swap into has
+@@ -8350,6 +8642,8 @@ export class Tabbrowser {
+     }
+     params.skipLoad = true;
+     let newTab = this.addWebTab("about:blank", params);
++    newTab._zenContentsVisible = true;
++    newTab.zenStaticLabel = aTab.zenStaticLabel;
+ 
+     aTab.container.tabDragAndDrop.finishAnimateTabMove();
+ 
+@@ -9189,7 +9483,7 @@ export class Tabbrowser {
+       // preventDefault(). It will still raise the window if appropriate.
+       return;
+     }
+-    this.selectedTab = tab;
++    this.documentGlobal.gZenWorkspaces.switchTabIfNeeded(tab);
+     this.documentGlobal.focus();
+     aEvent.preventDefault();
+   }
+@@ -9206,7 +9500,6 @@ export class Tabbrowser {
+ 
+   on_TabGroupCollapse(aEvent) {
+     aEvent.target.tabs.forEach(tab => {
+-      this.removeFromMultiSelectedTabs(tab);
+     });
+   }
+ 
+@@ -9554,7 +9847,9 @@ export class Tabbrowser {
+ 
+       let filter = this.#tabFilters.get(tab);
+       if (filter) {
++        try {
+         browser.webProgress.removeProgressListener(filter);
++        } catch {}
+ 
+         let listener = this.#tabListeners.get(tab);
+         if (listener) {
+@@ -10354,6 +10649,7 @@ class TabProgressListener {
+           aWebProgress.isTopLevel
+         ) {
+           this._tab.setAttribute("busy", "true");
++          if (!this._tab.selected) this._tab.setAttribute("unread", "true");
+           this.#tabbrowser._tabAttrModified(this._tab, ["busy"]);
+           this._tab._notselectedsinceload = !this._tab.selected;
+         }
+@@ -10434,6 +10730,7 @@ class TabProgressListener {
+       // known defaults. Note we use the original URL since about:newtab
+       // redirects to a prerendered page.
+       const shouldRemoveFavicon =
++        !this._tab.zenStaticIcon &&
+         !this._browser.mIconURL &&
+         !ignoreBlank &&
+         !(originalLocation.spec in FAVICON_DEFAULTS);
+@@ -10610,13 +10907,6 @@ class TabProgressListener {
+           this._browser.originalURI = aRequest.originalURI;
+         }
+ 
+-        if (!lazy.allowTransparentBrowser) {
+-          this._browser.toggleAttribute(
+-            "transparent",
+-            lazy.AIWindow.isAIWindowActive(this.#documentGlobal) &&
+-              lazy.AIWindow.isAIWindowContentPage(aLocation)
+-          );
+-        }
+       }
+ 
+       let userContextId = this._browser.getAttribute("usercontextid") || 0;
diff --git a/src/browser/components/tabbrowser/content/drag-and-drop-js.patch b/src/browser/components/tabbrowser/content/drag-and-drop-js.patch
index a1ae07ebc..4e0b97f1d 100644
--- a/src/browser/components/tabbrowser/content/drag-and-drop-js.patch
+++ b/src/browser/components/tabbrowser/content/drag-and-drop-js.patch
@@ -1,8 +1,8 @@
 diff --git a/browser/components/tabbrowser/content/drag-and-drop.js b/browser/components/tabbrowser/content/drag-and-drop.js
-index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8edf9bcf4 100644
+index f9623f82499e516050d523068e70ebaa4fe9a66a..95bcc078a86b4ec4b35f5916b7e4a5e305afba9e 100644
 --- a/browser/components/tabbrowser/content/drag-and-drop.js
 +++ b/browser/components/tabbrowser/content/drag-and-drop.js
-@@ -35,6 +35,9 @@
+@@ -42,6 +42,9 @@
     * @returns {MozTabbrowserTab|vbox}
     */
    const elementToMove = element => {
@@ -12,7 +12,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
      if (isTab(element) || isSplitViewWrapper(element)) {
        return element;
      }
-@@ -128,6 +131,9 @@
+@@ -140,6 +143,9 @@
        }
  
        let draggedTab = event.dataTransfer.mozGetDataAt(TAB_DROP_TYPE, 0);
@@ -22,15 +22,15 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
        if (
          (dropEffect == "move" || dropEffect == "copy") &&
          document == draggedTab.ownerDocument &&
-@@ -148,6 +154,7 @@
-           !draggedTab.group.collapsed
+@@ -161,6 +167,7 @@
          ) {
+           draggedTab.group.collapsedByDrag = true;
            draggedTab.group.collapsed = true;
 +          gZenFolders.animateGroupMove(draggedTab.group);
          }
  
          if (dropEffect == "move") {
-@@ -155,10 +162,6 @@
+@@ -168,10 +175,6 @@
  
            // Pinned tabs in expanded vertical mode are on a grid format and require
            // different logic to drag and drop.
@@ -41,7 +41,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            this._animateTabMove(event);
            return;
          }
-@@ -297,6 +300,10 @@
+@@ -310,6 +313,10 @@
  
        this._tabDropIndicator.hidden = true;
        event.stopPropagation();
@@ -52,7 +52,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
        if (draggedTab && dropEffect == "copy") {
          let duplicatedDraggedTab;
          let duplicatedTabs = [];
-@@ -324,12 +331,16 @@
+@@ -337,12 +344,16 @@
          let translateOffsetY = oldTranslateY % tabHeight;
          let newTranslateX = oldTranslateX - translateOffsetX;
          let newTranslateY = oldTranslateY - translateOffsetY;
@@ -73,7 +73,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
  
          if (this._tabbrowserTabs.isContainerVerticalPinnedGrid(draggedTab)) {
            // Update both translate axis for pinned vertical expanded tabs
-@@ -404,11 +415,13 @@
+@@ -417,11 +428,13 @@
            this._dragToPinPromoCard,
          ];
          let shouldPin =
@@ -87,7 +87,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            isTab(draggedTab) &&
            draggedTab.pinned &&
            this._tabbrowserTabs.arrowScrollbox.contains(event.target);
-@@ -484,6 +497,7 @@
+@@ -492,6 +505,7 @@
            }
          }
  
@@ -95,7 +95,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
          if (shouldTranslate) {
            this.#dropAnimationEndTime = Date.now() + DROP_ANIMATION_GRACE_MS;
            let translationPromises = [];
-@@ -496,7 +510,7 @@
+@@ -504,7 +518,7 @@
                  item.removeAttribute("tabdrop-samewindow");
                  resolve();
                };
@@ -104,7 +104,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
                  postTransitionCleanup();
                } else {
                  let onTransitionEnd = transitionendEvent => {
-@@ -580,7 +594,7 @@
+@@ -595,7 +609,7 @@
            if (tab.selected) {
              selectedTab = tab;
              indexForSelectedTab = newIndex;
@@ -113,7 +113,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
              const droppedIntoPinnedArea = dropIndex < gBrowser.pinnedTabCount;
              const newSplitView = gBrowser.adoptSplitView(tab, {
                elementIndex: droppedIntoPinnedArea
-@@ -605,7 +619,7 @@
+@@ -620,7 +634,7 @@
              }
            }
          }
@@ -122,7 +122,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            const newTab = gBrowser.adoptTab(selectedTab, {
              elementIndex: indexForSelectedTab,
              selectTab: selectedTab == draggedTab,
-@@ -639,10 +653,6 @@
+@@ -654,10 +668,6 @@
                this._tabbrowserTabs.dragAndDropElements[
                  gBrowser.pinnedTabCount + unpinnedSplitViews.length - 1
                ];
@@ -133,7 +133,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            }
          }
        } else {
-@@ -703,6 +713,7 @@
+@@ -717,6 +727,7 @@
  
            let nextItem = this._tabbrowserTabs.dragAndDropElements[newIndex];
            let tabGroup = isTab(nextItem) && nextItem.group;
@@ -141,7 +141,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            gBrowser.loadTabs(urls, {
              inBackground,
              replace,
-@@ -744,6 +755,22 @@
+@@ -758,6 +769,22 @@
          this._expandGroupOnDrop(draggedTab);
        }
        this._resetTabsAfterDrop(draggedTab);
@@ -164,7 +164,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
  
        if (
          dt.mozUserCancelled ||
-@@ -1074,11 +1101,10 @@
+@@ -1088,11 +1115,10 @@
          return this.#getHorizontalScrollboxDragTarget(event, ignoreSides);
        }
        while (target) {
@@ -180,7 +180,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            break;
          }
          target = target.parentNode;
-@@ -1108,6 +1134,9 @@
+@@ -1122,6 +1148,9 @@
            return null;
          }
        }
@@ -190,36 +190,43 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
        return target;
      }
  
-@@ -1170,14 +1199,20 @@
-       let releaseReservedSpace = () =>
-         this.#releaseSpaceInScrolledContent(periphery);
-       if (group.collapsed) {
--        // The group's tabs animate back to their full size, so hold on to the
--        // space reserved for them until they get there.
--        group.addEventListener(
--          "TabGroupAnimationComplete",
--          releaseReservedSpace,
--          { once: true }
--        );
--        group.collapsed = false;
-+        const expand = !group.hasAttribute("has-active");
-+        if (expand) {
-+          // The group's tabs animate back to their full size, so hold on to the
-+          // space reserved for them until they get there.
-+          group.addEventListener(
-+            "TabGroupAnimationComplete",
-+            releaseReservedSpace,
-+            { once: true }
-+          );
-+        } else {
-+          releaseReservedSpace();
-+        }
-+        group.collapsed = !expand;
-+        gZenFolders.animateGroupMove(group, true);
-       } else {
-         releaseReservedSpace();
-       }
-@@ -1362,7 +1397,6 @@
+@@ -1188,17 +1217,24 @@
+       let periphery = draggedTab.ownerDocument.getElementById(
+         "tabbrowser-arrowscrollbox-periphery"
+       );
+-      // The group's tabs animate back to their full size, so hold on to the
+-      // space reserved for them until they get there.
+-      group.addEventListener(
+-        "TabGroupAnimationComplete",
+-        () => {
+-          group.collapsedByDrag = false;
+-          this.#releaseSpaceInScrolledContent(periphery);
+-        },
+-        { once: true }
+-      );
+-      group.collapsed = false;
++      const expand = !group.hasAttribute("has-active");
++      if (expand) {
++        // The group's tabs animate back to their full size, so hold on to the
++        // space reserved for them until they get there.
++        group.addEventListener(
++          "TabGroupAnimationComplete",
++          () => {
++            group.collapsedByDrag = false;
++            this.#releaseSpaceInScrolledContent(periphery);
++          },
++          { once: true }
++        );
++      } else {
++        group.collapsedByDrag = false;
++        this.#releaseSpaceInScrolledContent(periphery);
++      }
++      group.collapsed = !expand;
++      gZenFolders.animateGroupMove(group, true);
+     }
+ 
+     /**
+@@ -1380,7 +1416,6 @@
          // using updateDragImage. On Linux, we can use a panel.
          if (platform == "win" || platform == "macosx") {
            captureListener = function () {
@@ -227,7 +234,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
            };
          } else {
            // Create a panel to use it in setDragImage
-@@ -1400,7 +1434,6 @@
+@@ -1418,7 +1453,6 @@
          );
          dragImageOffset = dragImageOffset * scale;
        }
@@ -235,7 +242,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
  
        // _dragData.offsetX/Y give the coordinates that the mouse should be
        // positioned relative to the corner of the new window created upon
-@@ -1419,7 +1452,7 @@
+@@ -1437,7 +1471,7 @@
        let dropEffect = this.getDropEffectForTabDrag(event);
        let isMovingInTabStrip = !fromTabList && dropEffect == "move";
        let collapseTabGroupDuringDrag =
@@ -244,7 +251,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
  
        tab._dragData = {
          offsetX: this._tabbrowserTabs.verticalMode
-@@ -1429,7 +1462,7 @@
+@@ -1447,7 +1481,7 @@
            ? event.screenY - window.screenY - tabOffset
            : event.screenY - window.screenY,
          scrollPos:
@@ -253,7 +260,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
              ? this._tabbrowserTabs.pinnedTabsContainer.scrollPosition
              : this._tabbrowserTabs.arrowScrollbox.scrollPosition,
          screenX: event.screenX,
-@@ -1522,6 +1555,7 @@
+@@ -1540,6 +1574,7 @@
        if (tabStripItemElement.hasAttribute("dragtarget")) {
          return;
        }
@@ -261,7 +268,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
        let isPinned = tab.pinned;
        let dragAndDropElements = this._tabbrowserTabs.dragAndDropElements;
        let isGrid = this._tabbrowserTabs.isContainerVerticalPinnedGrid(tab);
-@@ -1895,23 +1929,6 @@
+@@ -1913,23 +1948,6 @@
  
        // Slide the relevant tabs to their new position.
        // non-moving tabs adjust for RTL
@@ -285,7 +292,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
        // moving tabs don't adjust for RTL
        for (let item of selectedElements) {
          if (
-@@ -1960,7 +1977,6 @@
+@@ -1978,7 +1996,6 @@
        for (let item of this._tabbrowserTabs.dragAndDropElements) {
          delete item._moveTogetherSelectedTabsData;
          item = elementToMove(item);
@@ -293,7 +300,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
          item.removeAttribute("multiselected-move-together");
        }
      }
-@@ -2812,7 +2828,6 @@
+@@ -2830,7 +2847,6 @@
          tab.style.top = "";
          tab.style.maxWidth = "";
          tab.style.pointerEvents = "";
@@ -301,7 +308,7 @@ index 70b37f93c4e8ff4ad9a2452681e468d23914c1b5..dbf2d9c83dafbe0e0b4e6caf3835edc8
          tab.removeAttribute("small-stack");
          tab.removeAttribute("big-stack");
        }
-@@ -2821,11 +2836,9 @@
+@@ -2839,11 +2855,9 @@
        )) {
          label.style.width = "";
          label.style.maxWidth = "";
diff --git a/src/browser/components/tabbrowser/content/tabbrowser-js.patch b/src/browser/components/tabbrowser/content/tabbrowser-js.patch
deleted file mode 100644
index 05bdb13a4..000000000
--- a/src/browser/components/tabbrowser/content/tabbrowser-js.patch
+++ /dev/null
@@ -1,1177 +0,0 @@
-diff --git a/browser/components/tabbrowser/content/tabbrowser.js b/browser/components/tabbrowser/content/tabbrowser.js
-index 43180487a2fac15b7a65fac94f233eeed9094990..ef6d30eb681caeae48d15280687b3bc37dbadc37 100644
---- a/browser/components/tabbrowser/content/tabbrowser.js
-+++ b/browser/components/tabbrowser/content/tabbrowser.js
-@@ -514,6 +514,7 @@
-      * @type {MozBrowser[]}
-      */
-     get splitViewBrowsers() {
-+      return gZenViewSplitter.splitViewBrowsers;
-       const browsers = [];
-       if (this.#activeSplitView) {
-         for (const tab of this.#activeSplitView.tabs) {
-@@ -612,15 +613,66 @@
-       return this.tabContainer.visibleTabs;
-     }
- 
-+    zenHandleTabMove(...args) {
-+      return this.#handleTabMove(...args);
-+    }
-+
-+    get zenTabProgressListener() { return TabProgressListener; }
-+
-+    get _numVisiblePinTabsWithoutCollapsed() {
-+      let i = 0;
-+      for (let item of this.tabContainer.ariaFocusableItems) {
-+        if (this.isTabGroupLabel(item) && item.group?.pinned) {
-+          i += 1;
-+          continue;
-+        }
-+        if (!item.pinned && !item.hasAttribute("zen-glance-tab")) {
-+          break;
-+        }
-+        if (item.visible) {
-+          i += !item.hasAttribute("zen-glance-tab");
-+        }
-+      }
-+      return i;
-+    }
-+
-+    ungroupTabsUntilNoActive(tab) {
-+      if (!tab || !tab.group) return;
-+      const activeGroups = tab.group.activeGroups;
-+      if (activeGroups?.length) {
-+        const lastActiveGroup = activeGroups[activeGroups.length - 1];
-+        this.#handleTabMove(tab, () => {
-+          lastActiveGroup.after(tab);
-+        });
-+      }
-+    }
-+
-+    get _numZenEssentials() {
-+      let i = 0;
-+      for (let tab of this.tabs) {
-+        if (!tab.hasAttribute("zen-essential") && !tab.hasAttribute("zen-glance-tab")) {
-+          break;
-+        }
-+        i += !tab.hasAttribute("zen-glance-tab");
-+      }
-+      return i;
-+    }
-+
-     get pinnedTabCount() {
--      for (var i = 0; i < this.tabs.length; i++) {
--        if (!this.tabs[i].pinned) {
-+      let i = 0;
-+      for (let tab of this.tabs) {
-+        if (!tab.pinned && !tab.hasAttribute("zen-glance-tab")) {
-           break;
-         }
-+        i += !tab.hasAttribute("zen-glance-tab");
-       }
-       return i;
-     }
- 
-+    get tabsWithoutGlance() {
-+      return this.tabs.filter(tab => !tab.hasAttribute("zen-glance-tab"));
-+    }
-+
-     setSelectedTab(val, metricsContext = null) {
-       if (this.selectedTab === val) {
-         return;
-@@ -633,6 +685,9 @@
-       ) {
-         return;
-       }
-+      if (gZenWorkspaces.onBeforeTabSelect(val)) {
-+        return;
-+      }
-       // Update the tab
-       this.tabbox.selectedTab = val;
- 
-@@ -709,6 +764,10 @@
-         userContextId = parseInt(tabArgument.getAttribute("usercontextid"), 10);
-       }
- 
-+      if (typeof window._zenStartupUnsyncedUserContextId == 'number') {
-+        userContextId = window._zenStartupUnsyncedUserContextId;
-+      }
-+
-       if (openWindowInfo) {
-         userContextId = openWindowInfo.originAttributes.userContextId;
-       }
-@@ -810,6 +869,8 @@
-       this.tabpanels.appendChild(panel);
- 
-       let tab = this.tabs[0];
-+      gZenWorkspaces.handleInitialTab(tab, (!remoteType || remoteType === E10SUtils.PRIVILEGEDABOUT_REMOTE_TYPE) && !gZenUIManager.testingEnabled);
-+      tab._zenContentsVisible = true;
-       tab.linkedPanel = uniqueId;
-       this._selectedTab = tab;
-       this._selectedBrowser = browser;
-@@ -1179,18 +1240,24 @@
-      *   The context for the operation for telemetry purposes, defaults to an unknown context.
-      */
-     pinTab(aTab, { metricsContext = this.TabMetrics.UNKNOWN_CONTEXT } = {}) {
-+      aTab = gZenGlanceManager.getTabOrGlanceParent(aTab);
-       if (aTab.pinned || aTab == FirefoxViewHandler.tab) {
-         return;
-       }
- 
-       this.showTab(aTab);
-+      const handled = gZenFolders.handleTabPin(aTab);
-+      if (!handled) {
-+        this.ungroupTab(aTab);
-       this.#handleTabMove(aTab, () => {
-         let periphery = document.getElementById(
-           "pinned-tabs-container-periphery"
-         );
-         // If periphery is null, append to end
--        this.pinnedTabsContainer.insertBefore(aTab, periphery);
-+        this.tabContainer.tabDragAndDrop.handle_drop_transition(this.tabs[this.pinnedTabCount - 1], aTab, [aTab], false);
-+        aTab.hasAttribute("zen-essential") ? gZenWorkspaces.getEssentialsSection(aTab).appendChild(aTab) : this.pinnedTabsContainer.insertBefore(aTab, this.pinnedTabsContainer.lastChild)
-       });
-+      }
- 
-       aTab.setAttribute("pinned", "true");
-       this._updateTabBarForPinnedTabs();
-@@ -1207,16 +1274,25 @@
-      *   The context for the operation for telemetry purposes, defaults to an unknown context.
-      */
-     unpinTab(aTab, { metricsContext = this.TabMetrics.UNKNOWN_CONTEXT } = {}) {
-+      aTab = gZenGlanceManager.getTabOrGlanceParent(aTab);
-       if (!aTab.pinned) {
-         return;
-       }
- 
-       this.#handleTabMove(aTab, () => {
-+        const handled = gZenFolders.handleTabUnpin(aTab);
-+        if (!handled) {
-+          this.tabContainer.tabDragAndDrop.handle_drop_transition(this.tabs[this.pinnedTabCount + 1 /* empty + extra */], aTab, [aTab], true);
-+        }
-+
-         // we remove this attribute first, so that allTabs represents
-         // the moving of a tab from the pinned tabs container
-         // and back into arrowscrollbox.
-         aTab.removeAttribute("pinned");
--        this.tabContainer.arrowScrollbox.prepend(aTab);
-+        aTab.removeAttribute("zen-essential");
-+        if (!handled) {
-+          gZenWorkspaces.activeWorkspaceStrip.prepend(aTab);
-+        }
-       });
- 
-       aTab.style.marginInlineStart = "";
-@@ -1432,6 +1508,9 @@
- 
-       let LOCAL_PROTOCOLS = ["chrome:", "about:", "resource:", "data:"];
- 
-+      try {
-+        aIconURL = aTab.zenStaticIcon || aIconURL;
-+        gZenPinnedTabManager.onTabIconChanged(aTab, aIconURL);
-       if (
-         aIconURL &&
-         !LOCAL_PROTOCOLS.some(protocol => aIconURL.startsWith(protocol))
-@@ -1441,6 +1520,9 @@
-         );
-         return;
-       }
-+      } catch (e) {
-+        console.warn(e);
-+      }
- 
-       let browser = this.getBrowserForTab(aTab);
-       browser.mIconURL = aIconURL;
-@@ -1763,7 +1845,6 @@
- 
-       // Preview mode should not reset the owner
-       if (!this.#previewMode && !oldTab.selected) {
--        oldTab.owner = null;
-       }
- 
-       let lastRelatedTab = this.#lastRelatedTabMap.get(oldTab);
-@@ -1854,6 +1935,7 @@
-       if (!this.#previewMode) {
-         newTab.recordTimeFromUnloadToReload();
-         newTab.updateLastAccessed();
-+        newTab.removeAttribute("unread");
-         oldTab.updateLastAccessed();
-         // if this is the foreground window, update the last-seen timestamps.
-         if (this.documentGlobal == BrowserWindowTracker.getTopWindow()) {
-@@ -2068,6 +2150,9 @@
-       }
- 
-       let activeEl = document.activeElement;
-+      if (gURLBar._zenHandleUrlbarClose) {
-+        gURLBar._zenHandleUrlbarClose(true);
-+      }
-       // If focus is on the old tab, move it to the new tab.
-       if (activeEl == oldTab) {
-         newTab.focus();
-@@ -2106,7 +2191,7 @@
-       // Focus the location bar if it was previously focused for that tab.
-       // In full screen mode, only bother making the location bar visible
-       // if the tab is a blank one.
--      if (gURLBar.getBrowserState(newBrowser).urlbarFocused) {
-+      if (gURLBar.getBrowserState(newBrowser).urlbarFocused && (!gZenVerticalTabsManager._hasSetSingleToolbar || isBlankPageURL(newBrowser.currentURI?.spec))) {
-         let selectURL = () => {
-           if (this._asyncTabSwitching) {
-             // Set _awaitingSetURI flag to suppress popup notification
-@@ -2394,7 +2479,12 @@
-       return this._setTabLabel(aTab, aLabel);
-     }
- 
--    _setTabLabel(aTab, aLabel, { beforeTabOpen, isContentTitle, isURL } = {}) {
-+    _setTabLabel(aTab, aLabel, { beforeTabOpen, isContentTitle, isURL, _zenChangeLabelFlag } = {}) {
-+      if (!aTab._zenContentsVisible && !aTab._zenChangeLabelFlag && !aTab._labelIsInitialTitle && !gZenWorkspaces.privateWindowOrDisabled && !_zenChangeLabelFlag) {
-+        return false;
-+      }
-+      aLabel = (typeof aTab.zenStaticLabel === "string" && aTab.zenStaticLabel) ? aTab.zenStaticLabel : aLabel;
-+      gZenPinnedTabManager.onTabLabelChanged(aTab);
-       if (!aLabel || (isURL && /^about:reader\?url=/.test(aLabel))) {
-         return false;
-       }
-@@ -2520,7 +2610,7 @@
-         newIndex = this.selectedTab._tPos + 1;
-       }
- 
--      if (replace) {
-+      if (replace && !((targetTab || this.selectedTab)?.hasAttribute('zen-empty-tab'))) {
-         if (this.isTabGroupLabel(targetTab)) {
-           throw new Error(
-             "Replacing a tab group label with a tab is not supported"
-@@ -2795,6 +2885,7 @@
-       uriIsAboutBlank,
-       userContextId,
-       skipLoad,
-+      _forZenEmptyTab,
-     } = {}) {
-       let b = document.createXULElement("browser");
-       // Use the JSM global to create the permanentKey, so that if the
-@@ -2868,8 +2959,7 @@
-         // we use a different attribute name for this?
-         b.setAttribute("name", name);
-       }
--
--      if (AIWindow.isAIWindowActive(window) || this._allowTransparentBrowser) {
-+      if (this._allowTransparentBrowser || _forZenEmptyTab) {
-         b.setAttribute("transparent", "true");
-       }
- 
-@@ -3024,7 +3114,7 @@
- 
-       let panel = this.getPanel(browser);
-       let uniqueId = this._generateUniquePanelID();
--      panel.id = uniqueId;
-+      if (!panel.id?.startsWith("zen-")) panel.id = uniqueId;
-       aTab.linkedPanel = uniqueId;
- 
-       // Inject the <browser> into the DOM if necessary.
-@@ -3084,8 +3174,8 @@
-       // If we transitioned from one browser to two browsers, we need to set
-       // hasSiblings=false on both the existing browser and the new browser.
-       if (this.tabs.length == 2) {
--        this.tabs[0].linkedBrowser.browsingContext.hasSiblings = true;
--        this.tabs[1].linkedBrowser.browsingContext.hasSiblings = true;
-+        if (this.tabs[0].linkedBrowser.browsingContext) this.tabs[0].linkedBrowser.browsingContext.hasSiblings = true;
-+        if (this.tabs[1].linkedBrowser.browsingContext) this.tabs[1].linkedBrowser.browsingContext.hasSiblings = true;
-       } else {
-         aTab.linkedBrowser.browsingContext.hasSiblings = this.tabs.length > 1;
-       }
-@@ -3270,7 +3360,6 @@
-             this.selectedTab = this.addTrustedTab(BROWSER_NEW_TAB_URL, {
-               tabIndex: tab._tPos + 1,
-               userContextId: tab.userContextId,
--              tabGroup: tab.group,
-               focusUrlBar: true,
-             });
-             resolve(this.selectedBrowser);
-@@ -3380,6 +3469,10 @@
-         schemelessInput,
-         hasValidUserGestureActivation = false,
-         textDirectiveUserActivation = false,
-+        _forZenEmptyTab,
-+        essential,
-+        zenWorkspaceId,
-+        skipRoute = false,
-       } = {}
-     ) {
-       // all callers of addTab that pass a params object need to pass
-@@ -3390,10 +3483,25 @@
-         );
-       }
- 
-+      const beforeRouteResult = window.gZenSpaceRoutingManager.onBeforeAddTab(uriString, { skipRoute, pinned, tabGroup, fromExternal }, window);
-+      if (beforeRouteResult.shouldEarlyExit) {
-+        return null;
-+      }
-+
-+      let hasZenDefaultUserContextId = false;
-+      let zenForcedWorkspaceId = undefined;
-+      if (beforeRouteResult.isRouteFound && (typeof userContextId === "undefined" || fromExternal)) {
-+        userContextId = beforeRouteResult.userContextId;
-+        hasZenDefaultUserContextId = true;
-+      } else if (typeof gZenWorkspaces !== "undefined" && !_forZenEmptyTab) {
-+        [userContextId, hasZenDefaultUserContextId, zenForcedWorkspaceId] = gZenWorkspaces.getContextIdIfNeeded(userContextId, fromExternal, triggeringPrincipal);
-+      }
-+
-       if (!UserInteraction.running("browser.tabs.opening", window)) {
-         UserInteraction.start("browser.tabs.opening", "initting", window);
-       }
- 
-+      if (!gURLBar.hasAttribute("zen-newtab")) {
-       // If we're opening a foreground tab, set the owner by default.
-       ownerTab ??= inBackground ? null : this.selectedTab;
- 
-@@ -3401,6 +3509,7 @@
-       if (this.selectedTab.owner) {
-         this.selectedTab.owner = null;
-       }
-+      }
- 
-       // Find the tab that opened this one, if any. This is used for
-       // determining positioning, and inherited attributes such as the
-@@ -3453,6 +3562,22 @@
-           noInitialLabel,
-           skipBackgroundNotify,
-         });
-+        if (hasZenDefaultUserContextId) {
-+          t.setAttribute("zenDefaultUserContextId", "true");
-+        }
-+        if (zenWorkspaceId) {
-+          t.setAttribute("zen-workspace-id", zenWorkspaceId);
-+          t.setAttribute("change-workspace", "")
-+        } else if (zenForcedWorkspaceId !== undefined) {
-+          t.setAttribute("zen-workspace-id", zenForcedWorkspaceId);
-+          t.setAttribute("change-workspace", "")
-+        }
-+        if (_forZenEmptyTab) {
-+          t.setAttribute("zen-empty-tab", "true");
-+        }
-+        if (essential) {
-+          t.setAttribute("zen-essential", "true");
-+        }
-         if (insertTab) {
-           // Insert the tab into the tab container in the correct position.
-           this.#insertTabAtIndex(t, {
-@@ -3461,6 +3586,7 @@
-             ownerTab,
-             openerTab,
-             pinned,
-+            essential,
-             bulkOrderedOpen,
-             tabGroup: tabGroup ?? openerTab?.group,
-           });
-@@ -3479,6 +3605,7 @@
-           openWindowInfo,
-           skipLoad,
-           triggeringRemoteType,
-+          _forZenEmptyTab,
-         }));
- 
-         if (focusUrlBar) {
-@@ -3603,6 +3730,12 @@
-         }
-       }
- 
-+      if (typeof window.gZenVerticalTabsManager !== "undefined") {
-+        gZenVerticalTabsManager.animateItemOpen(t);
-+      }
-+      if (typeof window.gZenCompactModeManager !== "undefined" && !skipLoad && insertTab) {
-+        gZenCompactModeManager._onTabOpen(t, inBackground, beforeRouteResult);
-+      }
-       // Additionally send pinned tab events
-       if (pinned) {
-         this.#notifyPinnedStatus(t);
-@@ -3613,6 +3746,15 @@
-       if (!inBackground) {
-         this.selectedTab = t;
-       }
-+
-+      window.gZenSpaceRoutingManager.onAfterAddTab(
-+        uriString,
-+        t,
-+        { skipRoute: skipRoute || _forZenEmptyTab, fromExternal, pinned, tabGroup, inBackground },
-+        window,
-+        beforeRouteResult,
-+      );
-+
-       return t;
-     }
- 
-@@ -3836,6 +3978,7 @@
-         insertBefore = null,
-         isAdoptingGroup = false,
-         metricsContext = this.TabMetrics.UNKNOWN_CONTEXT,
-+        forSplitView = false,
-       } = {}
-     ) {
-       if (
-@@ -3846,9 +3989,6 @@
-             !this.isSplitViewWrapper(tabOrSplitView)
-         )
-       ) {
--        throw new Error(
--          "Cannot create tab group with zero tabs or split views"
--        );
-       }
- 
-       if (!color) {
-@@ -3869,9 +4009,14 @@
-         label,
-         isAdoptingGroup
-       );
--      this.tabContainer.insertBefore(
-+      if (forSplitView) {
-+        group.setAttribute('split-view-group', true);
-+      }
-+      group.essential = tabsAndSplitViews.some(tab => tab.hasAttribute("essential"));
-+      group.pinned = group.essential || tabsAndSplitViews.some(tab => tab.pinned);
-+      if (forSplitView && !insertBefore?.group?.isZenFolder) insertBefore = insertBefore?.group ?? insertBefore;
-+      insertBefore.before(
-         group,
--        insertBefore?.group ?? insertBefore
-       );
-       group.addTabs(tabsAndSplitViews, metricsContext);
- 
-@@ -3975,7 +4120,7 @@
-       }
- 
-       this.#handleTabMove(tab, () =>
--        gBrowser.tabContainer.insertBefore(tab, tab.group.nextElementSibling)
-+        tab.group.after(tab)
-       );
-     }
- 
-@@ -4061,6 +4206,7 @@
-         color: group.color,
-         insertBefore: newTabs[0],
-         isAdoptingGroup: true,
-+        forSplitView: group.hasAttribute('split-view-group'),
-       });
-     }
- 
-@@ -4271,6 +4417,7 @@
-         openWindowInfo,
-         skipLoad,
-         triggeringRemoteType,
-+        _forZenEmptyTab
-       }
-     ) {
-       // If we don't have a preferred remote type (or it is `NOT_REMOTE`), and
-@@ -4331,6 +4478,7 @@
-           openWindowInfo,
-           name,
-           skipLoad,
-+          _forZenEmptyTab
-         });
-       }
- 
-@@ -4544,9 +4692,9 @@
-         }
- 
-         // Add a new tab if needed.
--        if (!tab) {
-+        if (!tab || tab?._markedForReplacement) {
-           let createLazyBrowser =
--            restoreTabsLazily && !select && !tabData.pinned;
-+            restoreTabsLazily && !(tabData.pinned && !Services.prefs.getBoolPref("browser.sessionstore.restore_pinned_tabs_on_demand"));
- 
-           let url = "about:blank";
-           if (tabData.entries?.length) {
-@@ -4579,8 +4727,10 @@
-             insertTab: false,
-             skipLoad: true,
-             preferredRemoteType,
-+            _forZenEmptyTab: tabData.zenIsEmpty,
-           });
--
-+          tab._originalUrl = url;
-+          gZenSessionStore.restoreInitialTabData(tab, tabData);
-           if (select) {
-             tabToSelect = tab;
-           }
-@@ -4602,7 +4752,8 @@
-           this.pinTab(tab);
-           // Then ensure all the tab open/pinning information is sent.
-           this._fireTabOpen(tab, {});
--        } else if (tabData.groupId) {
-+        }
-+        if (tabData.groupId && tabGroupWorkingData.get(tabData.groupId)) {
-           let { groupId } = tabData;
-           const tabGroup = tabGroupWorkingData.get(groupId);
-           // if a tab refers to a tab group we don't know, skip any group
-@@ -4622,7 +4773,10 @@
-                 tabGroup.stateData.id,
-                 tabGroup.stateData.color,
-                 tabGroup.stateData.collapsed,
--                tabGroup.stateData.name
-+                tabGroup.stateData.name,
-+                tabGroup.stateData.pinned,
-+                tabGroup.stateData.essential,
-+                tabGroup.stateData.splitView,
-               );
-               tabsFragment.appendChild(tabGroup.node);
-             }
-@@ -4677,9 +4831,21 @@
-       // to remove the old selected tab.
-       if (tabToSelect) {
-         let leftoverTab = this.selectedTab;
-+        if (this._hasAlreadyInitializedZenSessionStore || !gZenWorkspaces.workspaceEnabled) {
-         this.selectedTab = tabToSelect;
-         this.removeTab(leftoverTab);
-+        } else {
-+          gZenWorkspaces._tabToRemoveForEmpty = leftoverTab;
-+          if (Services.prefs.getBoolPref("zen.workspaces.continue-where-left-off")) {
-+            gZenWorkspaces._tabToSelect = selectTab - 1; // -1 for the empty tab.
-+          }
-+          if (gZenWorkspaces._initialTab && !gZenVerticalTabsManager._canReplaceNewTab) {
-+            gZenWorkspaces._initialTab._shouldRemove = true;
-+          }
-+        }
-       }
-+      delete window.__isNewZenWindow;
-+      this._hasAlreadyInitializedZenSessionStore = true;
- 
-       if (tabs.length > 1 || !tabs[0].selected) {
-         this._updateTabsAfterInsert();
-@@ -4884,11 +5050,17 @@
-       if (ownerTab) {
-         tab.owner = ownerTab;
-       }
-+      if ((!tab.pinned && tabGroup?.isZenFolder && !Services.prefs.getBoolPref('zen.folders.owned-tabs-in-folder')) || (tabGroup && tabGroup.hasAttribute("split-view-group"))) {
-+        tabGroup = null;
-+      }
-+      if (openerTab?.hasAttribute("zen-glance-tab")) {
-+        openerTab = gZenGlanceManager.getTabOrGlanceParent(openerTab);
-+      }
- 
-       // Ensure we have an index if one was not provided.
-       if (typeof elementIndex != "number" && typeof tabIndex != "number") {
-         // Move the new tab after another tab if needed, to the end otherwise.
--        elementIndex = Infinity;
-+        elementIndex = Services.prefs.getBoolPref("zen.view.show-newtab-button-top") ? this._numVisiblePinTabsWithoutCollapsed : Infinity;
-         if (
-           !bulkOrderedOpen &&
-           ((openerTab &&
-@@ -4900,7 +5072,7 @@
-           let lastRelatedTab =
-             openerTab && this.#lastRelatedTabMap.get(openerTab);
-           let previousTab = lastRelatedTab || openerTab || this.selectedTab;
--          if (!tabGroup) {
-+          if (!tabGroup && pinned === previousTab.group?.pinned) {
-             tabGroup = previousTab.group;
-           }
-           if (
-@@ -4916,7 +5088,7 @@
-                 previousTab.splitview
-               ) + 1;
-           } else if (previousTab.visible) {
--            elementIndex = previousTab.elementIndex + 1;
-+            elementIndex = (typeof previousTab.elementIndex === 'undefined') ? elementIndex : (previousTab.elementIndex + 1);
-           } else if (previousTab == FirefoxViewHandler.tab) {
-             elementIndex = 0;
-           }
-@@ -4944,14 +5116,14 @@
-       }
-       // Ensure index is within bounds.
-       if (tab.pinned) {
--        index = Math.max(index, 0);
--        index = Math.min(index, this.pinnedTabCount);
-+        index = Math.max(index, tab.hasAttribute("zen-essential") ? 0 : this._numZenEssentials);
-+        index = Math.min(index, tab.hasAttribute("zen-essential") ? this._numZenEssentials : this._numVisiblePinTabsWithoutCollapsed);
-       } else {
--        index = Math.max(index, this.pinnedTabCount);
-+        index = Math.max(index, typeof elementIndex == "number" ? this._numVisiblePinTabsWithoutCollapsed : this.pinnedTabCount);
-         index = Math.min(index, allItems.length);
-       }
-       /** @type {MozTabbrowserTab|undefined} */
--      let itemAfter = allItems.at(index);
-+      let itemAfter = gZenGlanceManager.getTabOrGlanceParent(allItems.at(index));
- 
-       if (pinned && !itemAfter?.pinned) {
-         itemAfter = null;
-@@ -4968,7 +5140,7 @@
- 
-       this.tabContainer._invalidateCachedTabs();
- 
--      if (tabGroup) {
-+      if (tabGroup && !tabGroup.hasAttribute("split-view-group")) {
-         if (
-           (this.isTab(itemAfter) && itemAfter.group == tabGroup) ||
-           this.isSplitViewWrapper(itemAfter)
-@@ -4999,7 +5171,11 @@
-         const tabContainer = pinned
-           ? this.tabContainer.pinnedTabsContainer
-           : this.tabContainer;
-+        if (itemAfter) {
-+          itemAfter.before(tab);
-+        } else {
-         tabContainer.insertBefore(tab, itemAfter);
-+        }
-       }
- 
-       if (tab.group?.collapsed) {
-@@ -5014,6 +5190,7 @@
-       if (pinned) {
-         this._updateTabBarForPinnedTabs();
-       }
-+      gZenWorkspaces.fixTabInsertLocation(tab, itemAfter);
- 
-       TabBarVisibility.update();
-     }
-@@ -5577,6 +5754,7 @@
-         metricsContext,
-       } = {}
-     ) {
-+      tabs = tabs.filter(tab => !tab.hasAttribute("zen-empty-tab"));
-       // When 'closeWindowWithLastTab' pref is enabled, closing all tabs
-       // can be considered equivalent to closing the window.
-       if (
-@@ -5687,6 +5865,7 @@
-             closedTabCount -= 1;
-           }
-         }
-+        gZenUIManager.onTabClose(undefined);
- 
-         if (closedTabCount > 0) {
-           this.recordTabMetrics(
-@@ -5761,6 +5940,14 @@
-         return;
-       }
- 
-+      if (gZenWorkspaces.workspaceEnabled) {
-+        let newTab = gZenWorkspaces.handleTabBeforeClose(aTab, closeWindowWithLastTab);
-+        if (newTab) {
-+          this.selectedTab = newTab;
-+        }
-+      }
-+      animate &&= !aTab.group?.hasAttribute("split-view-group");
-+
-       let isVisibleTab = aTab.visible;
-       // We have to sample the tab width now, since _beginRemoveTab might
-       // end up modifying the DOM in such a way that aTab gets a new
-@@ -5768,6 +5955,9 @@
-       // state).
-       let tabWidth = window.windowUtils.getBoundsWithoutFlushing(aTab).width;
-       let isLastTab = this.#isLastTabInWindow(aTab);
-+      if (gZenGlanceManager.manageTabClose(aTab)) {
-+        return;
-+      }
-       if (
-         !this._beginRemoveTab(aTab, {
-           closeWindowFastpath: true,
-@@ -5778,13 +5968,14 @@
-           metricsContext,
-         })
-       ) {
-+        delete gZenWorkspaces._isClosingWindow;
-         Glean.browserTabclose.timeAnim.cancel(aTab._closeTimeAnimTimerId);
-         aTab._closeTimeAnimTimerId = null;
-         Glean.browserTabclose.timeNoAnim.cancel(aTab._closeTimeNoAnimTimerId);
-         aTab._closeTimeNoAnimTimerId = null;
-         return;
-       }
--
-+      gZenWorkspaces.handleTabBeforeRemove();
-       let lockTabSizing =
-         !this.tabContainer.verticalMode &&
-         !aTab.pinned &&
-@@ -5815,7 +6006,13 @@
-         // We're not animating, so we can cancel the animation stopwatch.
-         Glean.browserTabclose.timeAnim.cancel(aTab._closeTimeAnimTimerId);
-         aTab._closeTimeAnimTimerId = null;
--        this._endRemoveTab(aTab);
-+        if (animate && !gReduceMotion && !(gZenUIManager.testingEnabled && !gZenUIManager.profilingEnabled)) {
-+          gZenVerticalTabsManager.animateItemClose(aTab, (animate && !gReduceMotion)).then(() => {
-+            this._endRemoveTab(aTab);
-+          });
-+        } else {
-+          this._endRemoveTab(aTab);
-+        }
-         return;
-       }
- 
-@@ -5855,7 +6052,9 @@
-     get #shouldCloseWindowWithLastTab() {
-       return (
-         !window.toolbar.visible ||
--        Services.prefs.getBoolPref("browser.tabs.closeWindowWithLastTab")
-+        (Services.prefs.getBoolPref("browser.tabs.closeWindowWithLastTab") &&
-+          !gZenWorkspaces._isClosingWindow &&
-+          !gZenWorkspaces._removedByStartupPage)
-       );
-     }
- 
-@@ -5871,7 +6070,7 @@
-      */
-     #isLastTabInWindow(tab) {
-       for (const otherTab of this.tabs) {
--        if (otherTab != tab && otherTab.isOpen && !otherTab.hidden) {
-+        if (otherTab != tab && otherTab.isOpen && !otherTab.hidden && !otherTab.hasAttribute("zen-empty-tab")) {
-           return false;
-         }
-       }
-@@ -5982,6 +6181,7 @@
- 
-         newTab = true;
-       }
-+      gZenWorkspaces._removedByStartupPage = false;
-       aTab._endRemoveArgs = [closeWindow, newTab];
- 
-       // swapBrowsersAndCloseOther will take care of closing the window without animation.
-@@ -6029,13 +6229,7 @@
-       }
- 
-       if (newTab) {
--        this.addTrustedTab(BROWSER_NEW_TAB_URL, {
--          skipAnimation: true,
--          // In the event that insertAfterCurrent is set and the current tab is
--          // inside a group that is being closed we want to avoid creating the
--          // new tab inside that group.
--          tabIndex: 0,
--        });
-+        gZenWorkspaces.selectEmptyTab(BROWSER_NEW_TAB_URL);
-       } else {
-         TabBarVisibility.update();
-       }
-@@ -6192,6 +6386,7 @@
-         this.tabs[i]._tPos = i;
-       }
- 
-+      gZenWorkspaces.updateTabsContainers();
-       if (!this.#windowIsClosing) {
-         // update tab close buttons state
-         this.tabContainer._updateCloseButtons();
-@@ -6377,6 +6572,7 @@
-         memory_after: await getTotalMemoryUsage(),
-         time_to_unload_in_ms: timeElapsed,
-       });
-+      return true;
-     }
- 
-     /**
-@@ -6422,11 +6618,12 @@
-       }
- 
-       let excludeTabs = new Set(aExcludeTabs);
-+      gZenWorkspaces.getTabsToExclude(aTab).forEach(tab => excludeTabs.add(tab));
- 
-       // If this tab has a successor, it should be selectable, since
-       // hiding or closing a tab removes that tab as a successor.
-       if (aTab.successor && !excludeTabs.has(aTab.successor)) {
--        return aTab.successor;
-+        return gZenWorkspaces.findTabToBlur(aTab.successor);
-       }
- 
-       if (
-@@ -6434,13 +6631,13 @@
-         !excludeTabs.has(aTab.owner) &&
-         Services.prefs.getBoolPref("browser.tabs.selectOwnerOnClose")
-       ) {
--        return aTab.owner;
-+        return gZenWorkspaces.findTabToBlur(aTab.owner);
-       }
- 
-       // Try to find a remaining tab that comes after the given tab
-       let remainingTabs = Array.prototype.filter.call(
-         this.visibleTabs,
--        tab => !excludeTabs.has(tab)
-+        tab => !excludeTabs.has(tab) && gZenWorkspaces._shouldChangeToTab(tab) && tab !== aTab
-       );
- 
-       if (Services.prefs.getBoolPref("browser.tabs.selectMRUOnClose", false)) {
-@@ -6456,6 +6653,13 @@
-         }
-       }
- 
-+      if (remainingTabs.length > 0 && Services.prefs.getBoolPref("zen.tabs.select-recently-used-on-close")) {
-+        let mostRecentTab = remainingTabs.reduce((a, b) =>
-+          b.lastAccessed > a.lastAccessed ? b : a
-+        );
-+        return gZenWorkspaces.findTabToBlur(mostRecentTab);
-+      }
-+
-       let tab = this.tabContainer.findNextTab(aTab, {
-         direction: 1,
-         filter: _tab => remainingTabs.includes(_tab),
-@@ -6469,7 +6673,7 @@
-       }
- 
-       if (tab) {
--        return tab;
-+        return gZenWorkspaces.findTabToBlur(tab);
-       }
- 
-       // If no qualifying visible tab was found, see if there is a tab in
-@@ -6490,7 +6694,7 @@
-         });
-       }
- 
--      return tab;
-+      return gZenWorkspaces.findTabToBlur(tab);
-     }
- 
-     _blurTab(aTab) {
-@@ -6501,7 +6705,7 @@
-      * @returns {boolean}
-      *   False if swapping isn't permitted, true otherwise.
-      */
--    swapBrowsersAndCloseOther(aOurTab, aOtherTab) {
-+    swapBrowsersAndCloseOther(aOurTab, aOtherTab, zenCloseOther = true) {
-       // Do not allow transfering a private tab to a non-private window
-       // and vice versa.
-       if (
-@@ -6555,6 +6759,7 @@
-       // fire the beforeunload event in the process.  Close the other
-       // window if this was its last tab.
-       if (
-+        zenCloseOther &&
-         !remoteBrowser._beginRemoveTab(aOtherTab, {
-           adoptedByTab: aOurTab,
-           closeWindowWithLastTab: true,
-@@ -6566,7 +6771,7 @@
-       // If this is the last tab of the window, hide the window
-       // immediately without animation before the docshell swap, to avoid
-       // about:blank being painted.
--      let [closeWindow] = aOtherTab._endRemoveArgs;
-+      let [closeWindow] = !zenCloseOther ? [false] : aOtherTab._endRemoveArgs;
-       if (closeWindow) {
-         let win = aOtherTab.documentGlobal;
-         win.windowUtils.suppressAnimation(true);
-@@ -6700,11 +6905,13 @@
-       }
- 
-       // Finish tearing down the tab that's going away.
-+      if (zenCloseOther) {
-       if (closeWindow) {
-         aOtherTab.documentGlobal.close();
-       } else {
-         remoteBrowser._endRemoveTab(aOtherTab);
-       }
-+      }
- 
-       this.setTabTitle(aOurTab);
- 
-@@ -6928,10 +7135,10 @@
-       SessionStore.deleteCustomTabValue(aTab, "hiddenBy");
-     }
- 
--    hideTab(aTab, aSource) {
-+    hideTab(aTab, aSource, forZenWorkspaces = false) {
-       if (
-         aTab.hidden ||
--        aTab.pinned ||
-+        (aTab.pinned && !forZenWorkspaces) ||
-         aTab.selected ||
-         aTab.closing ||
-         // Tabs that are sharing the screen, microphone or camera cannot be hidden.
-@@ -6991,7 +7198,8 @@
-      * @param {object} [aOptions={}]
-      *   Key-value pairs that will be serialized into the features string.
-      */
--    replaceTabWithWindow(aTab, aOptions = {}) {
-+    replaceTabWithWindow(aTab, aOptions = {}, zenForceSync = false) {
-+      if (!this.isTab(aTab)) return; // TODO: Handle tab groups
-       if (this.tabs.length == 1) {
-         return null;
-       }
-@@ -7008,7 +7216,7 @@
-       // tell a new window to take the "dropped" tab
-       let args = Cc["@mozilla.org/array;1"].createInstance(Ci.nsIMutableArray);
-       args.appendElement(aTab.splitview ?? aTab);
--      return BrowserWindowTracker.openWindow({
-+      let win = BrowserWindowTracker.openWindow({
-         private: PrivateBrowsingUtils.isWindowPrivate(window),
-         features: Object.entries(aOptions)
-           .map(([key, value]) => `${key}=${value}`)
-@@ -7016,6 +7224,8 @@
-         openerWindow: window,
-         args,
-       });
-+      win._zenStartupSyncFlag = (zenForceSync || !Services.prefs.getBoolPref("zen.tabs.dnd-open-blank-window", true)) ? 'synced' : 'unsynced';
-+      return win;
-     }
- 
-     /**
-@@ -7142,7 +7352,7 @@
-      *   `true` if element is a `<tab-group>`
-      */
-     isTabGroup(element) {
--      return !!(element?.tagName == "tab-group");
-+      return !!(element?.tagName == "tab-group" || element?.tagName == "zen-folder");
-     }
- 
-     /**
-@@ -7214,8 +7424,8 @@
-       }
- 
-       // Don't allow mixing pinned and unpinned tabs.
--      if (this.isTab(element) && element.pinned) {
--        tabIndex = Math.min(tabIndex, this.pinnedTabCount - 1);
-+      if (element.pinned) {
-+        tabIndex = element.hasAttribute('zen-essential') ? Math.min(tabIndex, this._numZenEssentials - 1) : Math.min(Math.max(tabIndex, this._numZenEssentials), this.pinnedTabCount - 1);
-       } else {
-         tabIndex = Math.max(tabIndex, this.pinnedTabCount);
-       }
-@@ -7261,8 +7471,8 @@
-       this.#handleTabMove(
-         element,
-         () => {
--          let neighbor = this.tabs[tabIndex];
--          if (forceUngrouped && neighbor?.group) {
-+          let neighbor = gZenGlanceManager.getTabOrGlanceParent(this.tabs[tabIndex]);
-+          if ((forceUngrouped && neighbor?.group) || neighbor?.group?.hasAttribute("split-view-group")) {
-             neighbor = neighbor.group;
-           }
-           if (neighbor?.splitview) {
-@@ -7273,6 +7483,12 @@
-               return;
-             }
-           }
-+          if (element.group?.hasAttribute("split-view-group")) {
-+            element = element.group;
-+          }
-+          if (element.group?.hasAttribute("split-view-group") && neighbor == element.group) {
-+            return;
-+          }
- 
-           if (movingForwards && neighbor) {
-             neighbor.after(element);
-@@ -7346,23 +7562,31 @@
-     ) {
-       if (this.isTabGroupLabel(targetElement)) {
-         targetElement = targetElement.group;
--        if (!moveBefore && !targetElement.collapsed) {
-+        if (!moveBefore && !targetElement.collapsed && !targetElement.hasAttribute("split-view-group")) {
-           // Right after the tab group label = before the first tab in the tab group
-           targetElement = targetElement.tabs[0];
-           moveBefore = true;
-         }
-       }
--      if (this.isTabGroupLabel(element)) {
-+      if (this.isTabGroupLabel(element) || element.group?.hasAttribute("split-view-group")) {
-         element = element.group;
--        if (targetElement?.group) {
--          targetElement = targetElement.group;
--        }
-       }
- 
-       // Don't allow mixing pinned and unpinned tabs.
-+      targetElement = gZenGlanceManager.getTabOrGlanceParent(targetElement);
-+      if (targetElement?.classList.contains('tab-group-label-container')) {
-+        targetElement = targetElement.parentElement;
-+      }
-+      if (element.hasAttribute('zen-essential') && !targetElement?.hasAttribute('zen-essential')) {
-+        targetElement = this.tabsWithoutGlance[this._numZenEssentials - 1];
-+      } else
-       if (element.pinned && !targetElement?.pinned) {
--        targetElement = this.tabs[this.pinnedTabCount - 1];
-+        targetElement = this.tabsWithoutGlance[this.pinnedTabCount - 1];
-         moveBefore = false;
-+        if (!this.visibleTabs.includes(targetElement)) {
-+          targetElement = gZenWorkspaces.pinnedTabsContainer.querySelector('.pinned-tabs-container-separator')
-+          moveBefore = true;
-+        }
-       } else if (!element.pinned && targetElement && targetElement.pinned) {
-         // If the caller asks to move an unpinned element next to a pinned
-         // tab, move the unpinned element to be the first unpinned element
-@@ -7375,12 +7599,35 @@
-         //    move the tab group right before the first unpinned tab.
-         // 4. Moving a tab group and the first unpinned tab is grouped:
-         //    move the tab group right before the first unpinned tab's tab group.
--        targetElement = this.tabs[this.pinnedTabCount];
-+        targetElement = this.tabsWithoutGlance[this.pinnedTabCount];
-         if (targetElement.group) {
-           targetElement = targetElement.group;
-         }
-         moveBefore = true;
-       }
-+      if (!gZenFolders.canDropElement(element, targetElement)) {
-+        element = element.group;
-+      }
-+      if (!element.hasAttribute('zen-essential') && targetElement?.hasAttribute('zen-essential')) {
-+        targetElement = null;
-+        moveBefore = false;
-+      }
-+      // It is necessary to place the check below to avoid inserting an element
-+      // inside when the split group is the last element.
-+      if (targetElement?.group?.hasAttribute("split-view-group")) {
-+        targetElement = targetElement.group;
-+      }
-+      if (targetElement?.hasAttribute("zen-empty-tab")) {
-+        // When the folder is the last element in the pinned section,
-+        // targetElement is a tab with the zen-empty-tab attribute.
-+        // If the movement is from top to bottom, it must be redefined as a folder.
-+        if (!moveBefore) {
-+          targetElement = targetElement.group;
-+        } else {
-+          // Always insert an element after zen-empty-tab to avoid it moving from the first position
-+          moveBefore = false;
-+        }
-+      }
- 
-       // We want to include the splitview wrapper if it's the targetElement, but
-       // not in the case where we want to reverse tabs within the same splitview.
-@@ -7389,6 +7636,7 @@
-       }
- 
-       let getContainer = () =>
-+        element.hasAttribute("zen-essential") ? gZenWorkspaces.getEssentialsSection(element) :
-         element.pinned
-           ? this.tabContainer.pinnedTabsContainer
-           : this.tabContainer;
-@@ -7397,11 +7645,15 @@
-         element,
-         () => {
-           if (moveBefore) {
--            getContainer().insertBefore(element, targetElement);
-+            targetElement.parentElement.insertBefore(element, targetElement);
-           } else if (targetElement) {
-             targetElement.after(element);
-           } else {
-+            if (element.pinned) {
-+              getContainer().prepend(element);
-+            } else {
-             getContainer().appendChild(element);
-+            }
-           }
-         },
-         { metricsContext }
-@@ -7479,11 +7731,15 @@
-      *   The context for the operation for telemetry purposes.
-      */
-     moveTabToExistingGroup(aTab, aGroup, { metricsContext } = {}) {
--      if (!this.isTab(aTab)) {
-+      if (!this.isTab(aTab) && !aTab.hasAttribute('split-view-group')) {
-         throw new Error("Can only move a tab into a tab group");
-       }
--      if (aTab.pinned) {
--        return;
-+      if (aTab.pinned != !!aGroup.pinned) {
-+        if (aGroup.pinned) {
-+          this.pinTab(aTab);
-+        } else {
-+          this.unpinTab(aTab);
-+        }
-       }
-       if (aTab.group && aTab.group.id === aGroup.id) {
-         return;
-@@ -7557,6 +7813,7 @@
- 
-       let state = {
-         tabIndex: tab._tPos,
-+        workspaceId: tab.getAttribute("zen-workspace-id")
-       };
-       if (tab.visible) {
-         state.elementIndex = tab.elementIndex;
-@@ -7595,7 +7852,7 @@
-       let changedSplitView =
-         previousTabState.splitViewId != currentTabState.splitViewId;
- 
--      if (changedPosition || changedTabGroup || changedSplitView) {
-+      if (changedPosition || changedTabGroup || changedSplitView || (previousTabState.workspaceId != currentTabState.workspaceId)) {
-         tab.dispatchEvent(
-           new CustomEvent("TabMove", {
-             bubbles: true,
-@@ -7647,6 +7904,10 @@
- 
-       moveActionCallback();
- 
-+      gZenWorkspaces.makeSureEmptyTabIsFirst();
-+      gZenViewSplitter._maybeRemoveFakeBrowser(false);
-+      gZenViewSplitter._canDrop = false;
-+
-       // Clear tabs cache after moving nodes because the order of tabs may have
-       // changed.
-       this.tabContainer._invalidateCachedTabs();
-@@ -7694,7 +7955,22 @@
-      * @returns {object}
-      *    The new tab in the current window, null if the tab couldn't be adopted.
-      */
--    adoptTab(aTab, { elementIndex, tabIndex, selectTab = false } = {}) {
-+    adoptTab(aTab, { elementIndex, tabIndex, selectTab = false, spaceId = null } = {}) {
-+      if (window.gZenWorkspaces.currentWindowIsSyncing && aTab.documentGlobal.gZenWorkspaces?.currentWindowIsSyncing) {
-+        const tabId = aTab.id;
-+        const thisTab = window.gZenWindowSync.getItemFromWindow(window, tabId);
-+        if (thisTab) {
-+          // Just move the tab to the index
-+          this.moveTabTo(thisTab, { elementIndex, tabIndex });
-+          if (spaceId) {
-+            thisTab.setAttribute("zen-workspace-id", spaceId);
-+          }
-+          if (selectTab) {
-+            this.selectedTab = thisTab;
-+          }
-+          return thisTab;
-+        }
-+      }
-       // Swap the dropped tab with a new one we create and then close
-       // it in the other window (making it seem to have moved between
-       // windows). We also ensure that the tab we create to swap into has
-@@ -7737,6 +8013,8 @@
-       }
-       params.skipLoad = true;
-       let newTab = this.addWebTab("about:blank", params);
-+      newTab._zenContentsVisible = true;
-+      newTab.zenStaticLabel = aTab.zenStaticLabel;
- 
-       aTab.container.tabDragAndDrop.finishAnimateTabMove();
- 
-@@ -8516,7 +8794,7 @@
-         // preventDefault(). It will still raise the window if appropriate.
-         return;
-       }
--      this.selectedTab = tab;
-+      gZenWorkspaces.switchTabIfNeeded(tab);
-       window.focus();
-       aEvent.preventDefault();
-     }
-@@ -8533,7 +8811,6 @@
- 
-     on_TabGroupCollapse(aEvent) {
-       aEvent.target.tabs.forEach(tab => {
--        this.removeFromMultiSelectedTabs(tab);
-       });
-     }
- 
-@@ -8887,7 +9164,9 @@
- 
-         let filter = this.#tabFilters.get(tab);
-         if (filter) {
-+          try {
-           browser.webProgress.removeProgressListener(filter);
-+          } catch {}
- 
-           let listener = this.#tabListeners.get(tab);
-           if (listener) {
-@@ -9676,6 +9955,7 @@
-             aWebProgress.isTopLevel
-           ) {
-             this._tab.setAttribute("busy", "true");
-+            if (!this._tab.selected) this._tab.setAttribute("unread", "true");
-             gBrowser._tabAttrModified(this._tab, ["busy"]);
-             this._tab._notselectedsinceload = !this._tab.selected;
-           }
-@@ -9756,6 +10036,7 @@
-         // known defaults. Note we use the original URL since about:newtab
-         // redirects to a prerendered page.
-         const shouldRemoveFavicon =
-+          !this._tab.zenStaticIcon &&
-           !this._browser.mIconURL &&
-           !ignoreBlank &&
-           !(originalLocation.spec in FAVICON_DEFAULTS);
-@@ -9930,13 +10211,6 @@
-             this._browser.originalURI = aRequest.originalURI;
-           }
- 
--          if (!gBrowser._allowTransparentBrowser) {
--            this._browser.toggleAttribute(
--              "transparent",
--              AIWindow.isAIWindowActive(window) &&
--                AIWindow.isAIWindowContentPage(aLocation)
--            );
--          }
-         }
- 
-         let userContextId = this._browser.getAttribute("usercontextid") || 0;
diff --git a/src/browser/components/urlbar/UrlbarProviderHeuristicFallback-sys-mjs.patch b/src/browser/components/urlbar/UrlbarProviderHeuristicFallback-sys-mjs.patch
index e79eef7e8..7fc71ede2 100644
--- a/src/browser/components/urlbar/UrlbarProviderHeuristicFallback-sys-mjs.patch
+++ b/src/browser/components/urlbar/UrlbarProviderHeuristicFallback-sys-mjs.patch
@@ -1,15 +1,15 @@
 diff --git a/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs b/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs
-index cfc232f038cd491db32e0c0ca35622360dd9dec5..4806a725ddefa9d0709020d537eae5464249a294 100644
+index e32b02941a6019703212cede4660a24b88845120..5cb363ed20d49c1ae8abedecc3b08540406b7a1b 100644
 --- a/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs
 +++ b/browser/components/urlbar/UrlbarProviderHeuristicFallback.sys.mjs
-@@ -77,22 +77,26 @@ export class UrlbarProviderHeuristicFallback extends UrlbarProvider {
+@@ -76,22 +76,26 @@ export class UrlbarProviderHeuristicFallback extends UrlbarProvider {
          // Since we can't tell if this is a real URL and whether the user wants
          // to visit or search for it, we provide an alternative searchengine
          // match if the string looks like an alphanumeric origin or an e-mail.
 -        let str = queryContext.searchString;
 -        if (!URL.canParse(str)) {
 -          if (
--            lazy.UrlbarPrefs.get("keyword.enabled") &&
+-            queryContext.keywordEnabled &&
 -            (lazy.UrlUtils.looksLikeOrigin(str, {
 -              noIp: true,
 -              noPort: true,
@@ -24,7 +24,7 @@ index cfc232f038cd491db32e0c0ca35622360dd9dec5..4806a725ddefa9d0709020d537eae546
 +           }
 +        );
 +        if (
-+          lazy.UrlbarPrefs.get("keyword.enabled") &&
++          queryContext.keywordEnabled &&
 +          (lazy.UrlUtils.looksLikeUrl(searchCandidate) ||
 +            lazy.UrlUtils.looksLikeOrigin(searchCandidate, {
 +              allowPartialNumericalTLDs: true,
diff --git a/src/browser/components/urlbar/UrlbarUtils-sys-mjs.patch b/src/browser/components/urlbar/UrlbarUtils-sys-mjs.patch
deleted file mode 100644
index b3833b83b..000000000
--- a/src/browser/components/urlbar/UrlbarUtils-sys-mjs.patch
+++ /dev/null
@@ -1,16 +0,0 @@
-diff --git a/browser/components/urlbar/UrlbarUtils.sys.mjs b/browser/components/urlbar/UrlbarUtils.sys.mjs
-index 178cd5e84fda74a28b2de59b671b3399cc28fac4..b03c6e06de4ee9a95dcb4d33d7ac9f0b053be4e1 100644
---- a/browser/components/urlbar/UrlbarUtils.sys.mjs
-+++ b/browser/components/urlbar/UrlbarUtils.sys.mjs
-@@ -214,6 +214,11 @@ export var UrlbarUtils = {
-           return UrlbarShared.RESULT_GROUP.HEURISTIC_FALLBACK;
-         case "UrlbarProviderHistoryUrlHeuristic":
-           return UrlbarShared.RESULT_GROUP.HEURISTIC_HISTORY_URL;
-+        case "ZenUrlbarProviderGlobalActions":
-+          if (result.source == UrlbarShared.RESULT_SOURCE.WORKSPACES) {
-+            return UrlbarShared.RESULT_GROUP.ZEN_WORKSPACE;
-+          }
-+          return UrlbarShared.RESULT_GROUP.ZEN_ACTION;
-         case "UrlbarProviderOmnibox":
-           return UrlbarShared.RESULT_GROUP.HEURISTIC_OMNIBOX;
-         case "UrlbarProviderRestrictKeywordsAutofill":
diff --git a/src/browser/components/urlbar/content/UrlbarChildController-mjs.patch b/src/browser/components/urlbar/content/UrlbarChildController-mjs.patch
index cd89c299e..a8b0683d0 100644
--- a/src/browser/components/urlbar/content/UrlbarChildController-mjs.patch
+++ b/src/browser/components/urlbar/content/UrlbarChildController-mjs.patch
@@ -1,16 +1,16 @@
 diff --git a/browser/components/urlbar/content/UrlbarChildController.mjs b/browser/components/urlbar/content/UrlbarChildController.mjs
-index a17a4de079b69d2818388b33a2c1746cc6148c73..4fee63a22919972af08716db2d2de1c7549ff100 100644
+index 52ed36deac35d3de9f7f537313159fb4debe98a6..3bbc612a2e10eedafdabdaa8e17cf36831a6a27c 100644
 --- a/browser/components/urlbar/content/UrlbarChildController.mjs
 +++ b/browser/components/urlbar/content/UrlbarChildController.mjs
-@@ -438,7 +438,6 @@ export class UrlbarChildController {
-     const isMac = AppConstants.platform == "macosx";
+@@ -446,7 +446,6 @@ export class UrlbarChildController {
+     const isMac = UrlbarContentUtils.getPlatform() == "macosx";
      // Handle readline/emacs-style navigation bindings on Mac.
      if (
 -      isMac &&
        this.view.isOpen &&
        event.ctrlKey &&
        (event.key == "n" || event.key == "p")
-@@ -630,6 +629,8 @@ export class UrlbarChildController {
+@@ -644,6 +643,8 @@ export class UrlbarChildController {
              });
            }
            event.preventDefault();
@@ -19,7 +19,7 @@ index a17a4de079b69d2818388b33a2c1746cc6148c73..4fee63a22919972af08716db2d2de1c7
          }
          break;
        }
-@@ -934,6 +935,10 @@ export class UrlbarChildController {
+@@ -905,6 +906,10 @@ export class UrlbarChildController {
        }
        reuseEmpty = true;
      }
@@ -30,7 +30,7 @@ index a17a4de079b69d2818388b33a2c1746cc6148c73..4fee63a22919972af08716db2d2de1c7
      // The browser window exists only in chrome; a content-process input has no
      // tab to reuse, so `gBrowser` is absent and the reuse is skipped.
      if (
-@@ -943,6 +948,10 @@ export class UrlbarChildController {
+@@ -914,6 +919,10 @@ export class UrlbarChildController {
      ) {
        where = "current";
      }
diff --git a/src/browser/components/urlbar/content/UrlbarInput-mjs.patch b/src/browser/components/urlbar/content/UrlbarInputBase-mjs.patch
similarity index 81%
rename from src/browser/components/urlbar/content/UrlbarInput-mjs.patch
rename to src/browser/components/urlbar/content/UrlbarInputBase-mjs.patch
index e9d45bf24..09797f002 100644
--- a/src/browser/components/urlbar/content/UrlbarInput-mjs.patch
+++ b/src/browser/components/urlbar/content/UrlbarInputBase-mjs.patch
@@ -1,22 +1,21 @@
-diff --git a/browser/components/urlbar/content/UrlbarInput.mjs b/browser/components/urlbar/content/UrlbarInput.mjs
-index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36d7d74e8e 100644
---- a/browser/components/urlbar/content/UrlbarInput.mjs
-+++ b/browser/components/urlbar/content/UrlbarInput.mjs
-@@ -88,6 +88,13 @@ const lazy = XPCOMUtils.declareLazy({
-   logger: () => UrlbarShared.getLogger({ prefix: "Input" }),
- });
+diff --git a/browser/components/urlbar/content/UrlbarInputBase.mjs b/browser/components/urlbar/content/UrlbarInputBase.mjs
+index 8be35b58c5369e123ca69426e852e3849bf75513..170cffbdd12a72dab15976cdab9207dc4292d4e6 100644
+--- a/browser/components/urlbar/content/UrlbarInputBase.mjs
++++ b/browser/components/urlbar/content/UrlbarInputBase.mjs
+@@ -83,6 +83,12 @@ if (lazy) {
+       Ci.nsIURLQueryStringStripper,
+     ],
+   });
++  XPCOMUtils.defineLazyPreferenceGetter(
++    lazy,
++    "ZEN_URLBAR_BEHAVIOR",
++    "zen.urlbar.behavior",
++    'default'
++  );
+ }
  
-+XPCOMUtils.defineLazyPreferenceGetter(
-+  lazy,
-+  "ZEN_URLBAR_BEHAVIOR",
-+  "zen.urlbar.behavior",
-+  'default'
-+);
-+
- const UNLIMITED_MAX_RESULTS = 99;
- 
- let getBoundsWithoutFlushing = element =>
-@@ -771,7 +778,16 @@ ${
+ const logger = () => UrlbarShared.getLogger({ prefix: "Input" });
+@@ -917,7 +923,16 @@ ${
      // See _on_select().  HTMLInputElement.select() dispatches a "select"
      // event but does not set the primary selection.
      this._suppressPrimaryAdjustment = true;
@@ -33,7 +32,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      this._suppressPrimaryAdjustment = false;
    }
  
-@@ -846,6 +862,10 @@ ${
+@@ -992,6 +1007,10 @@ ${
      hideSearchTerms = false,
      isSameDocument = false,
    } = {}) {
@@ -44,7 +43,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      if (!this.#isAddressbar) {
        throw new Error(
          "Cannot set URI for UrlbarInput that is not an address bar"
-@@ -1143,7 +1163,16 @@ ${
+@@ -1289,7 +1308,16 @@ ${
        this.searchModeSwitcher?.updateSearchIcon();
      }
  
@@ -61,7 +60,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
    }
  
    /**
-@@ -1255,6 +1284,9 @@ ${
+@@ -1401,6 +1429,9 @@ ${
        where,
        query: searchString,
      });
@@ -71,7 +70,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      this.controller.openSERP(
        engine.id,
        searchString,
-@@ -1726,7 +1758,11 @@ ${
+@@ -1884,7 +1915,11 @@ ${
      openParams.avoidBrowserFocus = keepViewOpen;
  
      if (!this.#providesSearchMode(result) && !keepViewOpen) {
@@ -84,12 +83,12 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      }
  
      if (isCanonized) {
-@@ -3016,6 +3052,42 @@ ${
+@@ -3181,6 +3216,42 @@ ${
      await this.#updateLayoutBreakoutDimensions();
    }
  
 +  zenFormatURLValue() {
-+    return this.#lazy.valueFormatter._formatURL();
++    return this.#getValueFormatter().update();
 +  }
 +
 +  get zenUrlbarBehavior() {
@@ -127,7 +126,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
    startLayoutExtend() {
      if (!this.#allowBreakout || this.hasAttribute("breakout-extend")) {
        // Do not expand if the Urlbar does not support being expanded or it is
-@@ -3030,6 +3102,13 @@ ${
+@@ -3195,6 +3266,13 @@ ${
      this.toggleAttribute("breakout-extend", true);
      this.#updateTextboxPosition();
  
@@ -141,7 +140,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      // Enable the animation only after the first extend call to ensure it
      // doesn't run when opening a new window.
      if (!this.hasAttribute("breakout-extend-animate")) {
-@@ -3053,6 +3132,29 @@ ${
+@@ -3218,6 +3296,29 @@ ${
        return;
      }
  
@@ -171,7 +170,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      this.toggleAttribute("breakout-extend", false);
      this.#updateTextboxPosition();
    }
-@@ -3091,7 +3193,7 @@ ${
+@@ -3256,7 +3357,7 @@ ${
      forceUnifiedSearchButtonAvailable = false
    ) {
      let prevState = this.getAttribute("pageproxystate");
@@ -180,20 +179,20 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      this.setAttribute("pageproxystate", state);
      this._inputContainer.setAttribute("pageproxystate", state);
      this._identityBox?.setAttribute("pageproxystate", state);
-@@ -3355,10 +3457,12 @@ ${
+@@ -3533,7 +3634,11 @@ ${
+       return;
      }
  
-     this.style.top = px(
+-    this.style.top = px(getUntransformedTop(this.parentNode));
++    this.style.top = px(
 +      this.window.gZenVerticalTabsManager._hasSetSingleToolbar ?
-       this.parentNode.getBoxQuads({
-         ignoreTransforms: true,
-         flush: false,
-       })[0].p1.y
-+      : (AppConstants.platform == "macosx" ? -2 : -5)
-     );
++      getUntransformedTop(this.parentNode)
++      : (UrlbarContentUtils.getPlatform() == "macosx" ? -2 : -5)
++    );
    }
  
-@@ -3417,9 +3521,10 @@ ${
+   #updateTextboxPositionNextFrame() {
+@@ -3591,9 +3696,10 @@ ${
            return;
          }
  
@@ -205,7 +204,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
          );
  
          if (this.#breakoutBlockerCount) {
-@@ -3929,6 +4034,7 @@ ${
+@@ -4108,6 +4214,7 @@ ${
    }
  
    _toggleActionOverride(event) {
@@ -213,7 +212,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      if (
        event.keyCode == KeyEvent.DOM_VK_SHIFT ||
        event.keyCode == KeyEvent.DOM_VK_ALT ||
-@@ -4027,9 +4133,10 @@ ${
+@@ -4206,9 +4313,10 @@ ${
      if (!this.#isAddressbar) {
        return val;
      }
@@ -226,36 +225,36 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
 +        : val;
      // Only trim value if the directionality doesn't change to RTL and we're not
      // showing a strikeout https protocol.
-     return this.controller.isTextDirectionRTL(trimmedValue) ||
-@@ -4235,6 +4342,11 @@ ${
+     return UrlbarContentUtils.isTextDirectionRTL(trimmedValue, window) ||
+@@ -4410,6 +4518,11 @@ ${
      keepViewOpen = false,
      browserId = null,
    }) {
 +    where = this.window.gZenUIManager.getOpenUILinkWhere(
-+      url,
++      loadRequest.urlLoad?.url ?? "",
 +      this.window.gBrowser.selectedBrowser,
 +      where
 +    );
-     let userTypedValue;
-     if (this.#isAddressbar && where == "current") {
-       // Make sure URL is formatted properly (don't show punycode).
-@@ -4576,6 +4688,7 @@ ${
-       this.setResultForCurrentValue(null);
-       this.handleCommand();
-       this.controller.clearLastQueryContextCache();
-+      this.view.close();
+     let keyDownEnterDeferred;
+     if (
+       this._keyDownEnterDeferred &&
+@@ -4731,6 +4844,7 @@ ${
+           this.setResultForCurrentValue(null);
+           this.handleCommand();
+           this.controller.clearLastQueryContextCache();
++          this.view.close();
  
-       this._suppressStartQuery = false;
-     });
-@@ -4583,7 +4696,6 @@ ${
-     contextMenu.addEventListener("popupshowing", () => {
-       // Close the results pane when the input field contextual menu is open,
-       // because paste and go doesn't want a result selection.
--      this.view.close();
+           this._suppressStartQuery = false;
+         });
+@@ -4742,7 +4856,6 @@ ${
+         // Close the results pane, because paste and go doesn't want a result
+         // selection. This has to happen before the menu opens: ending
+         // breakout-extend once it's open keeps it from showing (bug 2037468).
+-        this.view.close();
  
-       let controller =
-         this.document.commandDispatcher.getControllerForCommand("cmd_paste");
-@@ -4850,7 +4962,11 @@ ${
+         let controller =
+           this.document.commandDispatcher.getControllerForCommand("cmd_paste");
+@@ -5025,7 +5138,11 @@ ${
      if (!engineName && !source && !this.hasAttribute("searchmode")) {
        return;
      }
@@ -268,7 +267,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      if (this._searchModeIndicatorTitle) {
        this._searchModeIndicatorTitle.textContent = "";
        this._searchModeIndicatorTitle.removeAttribute("data-l10n-id");
-@@ -5149,6 +5265,7 @@ ${
+@@ -5335,6 +5452,7 @@ ${
  
      this.document.l10n.setAttributes(
        this.inputField,
@@ -276,10 +275,10 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
        l10nId,
        l10nId == "urlbar-placeholder-with-name"
          ? { name: engineName }
-@@ -5199,6 +5316,12 @@ ${
+@@ -5385,6 +5503,12 @@ ${
      }
  
-     lazy.logger.debug("Blur Event");
+     logger().debug("Blur Event");
 +    if (
 +      this.document.commandDispatcher.focusedElement == this.inputField &&
 +      !UrlbarPrefs.get("closeOnWindowBlur")
@@ -289,7 +288,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      // We cannot count every blur events after a missed engagement as abandoment
      // because the user may have clicked on some view element that executes
      // a command causing a focus change. For example opening preferences from
-@@ -5276,6 +5399,11 @@ ${
+@@ -5464,6 +5588,11 @@ ${
    }
  
    _on_click(event) {
@@ -301,7 +300,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
      switch (event.target) {
        case this.inputField:
        case this._inputContainer:
-@@ -5371,10 +5499,11 @@ ${
+@@ -5558,10 +5687,11 @@ ${
        }
        if (untrim) {
          this.setValue(this._untrimmedValue);
@@ -314,7 +313,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
        this.view.autoOpen({ event });
      } else {
        if (this._untrimOnFocusAfterKeydown) {
-@@ -5414,9 +5543,16 @@ ${
+@@ -5605,9 +5735,16 @@ ${
    }
  
    _on_mousedown(event) {
@@ -332,7 +331,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
          if (
            event.composedTarget != this.inputField &&
            event.composedTarget != this._inputContainer
-@@ -5426,6 +5562,10 @@ ${
+@@ -5617,6 +5754,10 @@ ${
  
          this.focusedViaMousedown = !this.focused;
          this.#preventClickSelectsAll = this.focused;
@@ -343,7 +342,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
  
          // Keep the focus status, since the attribute may be changed
          // upon calling this.focus().
-@@ -5463,7 +5603,7 @@ ${
+@@ -5654,7 +5795,7 @@ ${
          // view open on tab switch, and the TabSelect event arrived earlier.
          // Also ignore mousedown on the urlbarView context menu: opening/closing the
          // view is already handled by the result opening flow.
@@ -352,7 +351,7 @@ index 319fb6870ec18d87b9f1263bd960edaa39b0447c..1746a052c304e7988447fdb869ad2e36
            break;
          }
  
-@@ -5754,7 +5894,7 @@ ${
+@@ -5948,7 +6089,7 @@ ${
      // When we are in actions search mode we can show more results so
      // increase the limit.
      let maxResults =
diff --git a/src/browser/components/urlbar/content/UrlbarShared-mjs.patch b/src/browser/components/urlbar/content/UrlbarShared-mjs.patch
index a36136808..e2622c8f6 100644
--- a/src/browser/components/urlbar/content/UrlbarShared-mjs.patch
+++ b/src/browser/components/urlbar/content/UrlbarShared-mjs.patch
@@ -1,8 +1,8 @@
 diff --git a/browser/components/urlbar/content/UrlbarShared.mjs b/browser/components/urlbar/content/UrlbarShared.mjs
-index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36119ae73e 100644
+index 0ac5330223c84fbb98880a5c2d83ae58a8f3079e..f9d3d27333f5552404bd8a1138fb1e5d6150a3d8 100644
 --- a/browser/components/urlbar/content/UrlbarShared.mjs
 +++ b/browser/components/urlbar/content/UrlbarShared.mjs
-@@ -100,6 +100,7 @@ export const UrlbarShared = {
+@@ -158,6 +158,7 @@ export const UrlbarShared = {
      // `looksLikeOrigin()` returned `LOOKS_LIKE_ORIGIN.OTHER` for this token.
      // It may or may not be an origin.
      POSSIBLE_ORIGIN_BUT_SEARCH_ALLOWED: 12,
@@ -10,7 +10,7 @@ index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36
    }),
  
    /**
-@@ -120,6 +121,7 @@ export const UrlbarShared = {
+@@ -178,6 +179,7 @@ export const UrlbarShared = {
      TITLE: "#",
      URL: "$",
      ACTION: ">",
@@ -18,7 +18,7 @@ index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36
    }),
  
    // Defines UrlbarResult types.
-@@ -165,6 +167,8 @@ export const UrlbarShared = {
+@@ -223,6 +225,8 @@ export const UrlbarShared = {
      OTHER_NETWORK: 6,
      ADDON: 7,
      ACTIONS: 8,
@@ -27,7 +27,7 @@ index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36
    }),
  
    // Results are categorized into groups to help the muxer compose them.  See
-@@ -200,6 +204,8 @@ export const UrlbarShared = {
+@@ -258,6 +262,8 @@ export const UrlbarShared = {
      SEMANTIC_HISTORY: "semanticHistory",
      SUGGESTED_INDEX: "suggestedIndex",
      TAIL_SUGGESTION: "tailSuggestion",
@@ -36,7 +36,7 @@ index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36
    }),
  
    // Defines provider types.
-@@ -385,6 +391,14 @@ export const UrlbarShared = {
+@@ -443,6 +449,14 @@ export const UrlbarShared = {
          telemetryLabel: "actions",
          uiLabel: "urlbar-searchmode-actions3",
        },
@@ -51,7 +51,7 @@ index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36
      ]);
    },
  
-@@ -402,6 +416,7 @@ export const UrlbarShared = {
+@@ -460,6 +474,7 @@ export const UrlbarShared = {
      if (UrlbarPrefs.get("scotchBonnet.enableOverride")) {
        keys.push(this.RESTRICT_TOKENS.ACTION);
      }
@@ -59,3 +59,15 @@ index 4e67dad66ae006842abc6eed547e4a244320d57a..393b61b4d2543c73e60afd334a353f36
      return new Set(keys);
    },
  
+@@ -1032,6 +1047,11 @@ export const UrlbarShared = {
+           return UrlbarShared.RESULT_GROUP.HEURISTIC_FALLBACK;
+         case "UrlbarProviderHistoryUrlHeuristic":
+           return UrlbarShared.RESULT_GROUP.HEURISTIC_HISTORY_URL;
++        case "ZenUrlbarProviderGlobalActions":
++          if (result.source == UrlbarShared.RESULT_SOURCE.WORKSPACES) {
++            return UrlbarShared.RESULT_GROUP.ZEN_WORKSPACE;
++          }
++          return UrlbarShared.RESULT_GROUP.ZEN_ACTION;
+         case "UrlbarProviderOmnibox":
+           return UrlbarShared.RESULT_GROUP.HEURISTIC_OMNIBOX;
+         case "UrlbarProviderRestrictKeywordsAutofill":
diff --git a/src/browser/modules/ExtensionsUI-sys-mjs.patch b/src/browser/modules/ExtensionsUI-sys-mjs.patch
index 8035e51e4..148a3d536 100644
--- a/src/browser/modules/ExtensionsUI-sys-mjs.patch
+++ b/src/browser/modules/ExtensionsUI-sys-mjs.patch
@@ -1,10 +1,10 @@
 diff --git a/browser/modules/ExtensionsUI.sys.mjs b/browser/modules/ExtensionsUI.sys.mjs
-index 95a4b6e40bd568c3ea5003b648b0acbf96bbb725..6ab8a658721aa6470d482dc958e4b3ac78f49f44 100644
+index 73ef024602cb4554a024de4ddef83f492adc33ef..959c3403a48a3e4294ad5d2f72bad0e5d4fbfd75 100644
 --- a/browser/modules/ExtensionsUI.sys.mjs
 +++ b/browser/modules/ExtensionsUI.sys.mjs
-@@ -502,7 +502,7 @@ export var ExtensionsUI = {
-         eventCallback,
-         removeOnDismissal: true,
+@@ -507,7 +507,7 @@ export var ExtensionsUI = {
+         // right after the panel opens can't accidentally grant permissions).
+         autofocus: true,
          popupOptions: {
 -          position: "bottomright topright",
 +          position: window.gZenUIManager.panelUIPosition(),
diff --git a/src/browser/themes/shared/tabbrowser/content-area-css.patch b/src/browser/themes/shared/tabbrowser/content-area-css.patch
index d8db6cb91..95d32f63e 100644
--- a/src/browser/themes/shared/tabbrowser/content-area-css.patch
+++ b/src/browser/themes/shared/tabbrowser/content-area-css.patch
@@ -1,8 +1,8 @@
 diff --git a/browser/themes/shared/tabbrowser/content-area.css b/browser/themes/shared/tabbrowser/content-area.css
-index 2374ed38bd9361d6c7e1886117099c6761e403b8..72f1f52a13096f19ca4009037ad0cdc880775ff7 100644
+index 86400b643c8b2af4207d226fbd6d91e5e74548b9..3044e4ab87b7ebcfaa2ac624680da1cc5653c861 100644
 --- a/browser/themes/shared/tabbrowser/content-area.css
 +++ b/browser/themes/shared/tabbrowser/content-area.css
-@@ -239,7 +239,6 @@
+@@ -166,7 +166,6 @@
    min-width: 0;
  
    /* We want to be able to show the frame color behind the clipped radiused corner */
@@ -10,7 +10,7 @@ index 2374ed38bd9361d6c7e1886117099c6761e403b8..72f1f52a13096f19ca4009037ad0cdc8
  
    display: grid;
    /**
-@@ -425,7 +424,6 @@
+@@ -355,7 +354,6 @@
    }
  
    browser:is([blank], [pendingpaint]) {
@@ -18,21 +18,21 @@ index 2374ed38bd9361d6c7e1886117099c6761e403b8..72f1f52a13096f19ca4009037ad0cdc8
    }
  
    /* Exclude browsers with smartwindow-content attribute which inherit
-@@ -865,7 +863,7 @@ split-view-footer {
+@@ -735,7 +733,7 @@ split-view-footer {
  
  .dialogStack {
    z-index: var(--browser-stack-z-index-dialog-stack);
 -  position: absolute;
 +  position: fixed;
-   inset: 0;
+ 
    /* --browser-with-dialog set on browser[tabDialogShowing], we want to position the overlay
       only on the top of the <browser> element so it doesn't overlap the DevTools toolbox */
-@@ -1034,7 +1032,7 @@ split-view-footer {
+@@ -909,7 +907,7 @@ split-view-footer {
  
  .dialogOverlay[topmost="true"],
  #window-modal-dialog::backdrop {
 -  background-color: var(--background-color-overlay);
 +  background-color: light-dark(rgba(255, 255, 255, .3), rgba(0, 0, 0, .3));
-   border-radius: var(--chrome-block-radius);
+ }
  
-   .browserSidebarContainer.responsive-mode & {
+ .dialogOverlay[hideContent="true"][topmost="true"] {
diff --git a/src/browser/themes/shared/toolbarbuttons-css.patch b/src/browser/themes/shared/toolbarbuttons-css.patch
index 917122e5e..930b816fe 100644
--- a/src/browser/themes/shared/toolbarbuttons-css.patch
+++ b/src/browser/themes/shared/toolbarbuttons-css.patch
@@ -1,5 +1,5 @@
 diff --git a/browser/themes/shared/toolbarbuttons.css b/browser/themes/shared/toolbarbuttons.css
-index 94b1a2a841d8fd47a491616d52e5bf544f0c0bf9..9e98266b98c6b66fed26fec12fa3391fc5fcc79b 100644
+index bbf906c7bf1d6f0d71744953aeeb750c5181639a..dd116e22c38dc376c9c6b34dfa569bf4661a8971 100644
 --- a/browser/themes/shared/toolbarbuttons.css
 +++ b/browser/themes/shared/toolbarbuttons.css
 @@ -13,20 +13,6 @@
@@ -23,7 +23,7 @@ index 94b1a2a841d8fd47a491616d52e5bf544f0c0bf9..9e98266b98c6b66fed26fec12fa3391f
    &:where([uidensity="compact"]) {
      --toolbarbutton-padding-inner: var(--toolbarbutton-padding-inner-compact);
      --bookmark-block-padding: 1px;
-@@ -123,9 +109,7 @@
+@@ -119,9 +105,7 @@
  #TabsToolbar {
    /* Override the inner padding to ensure the dimensions match the tabs, but also making sure
       different types of buttons (combined-buttons-dropmarker or text) still look correct. */
@@ -33,18 +33,16 @@ index 94b1a2a841d8fd47a491616d52e5bf544f0c0bf9..9e98266b98c6b66fed26fec12fa3391f
  }
  
  /* Primary toolbar buttons */
-@@ -205,8 +189,8 @@ toolbar .toolbarbutton-1 {
+@@ -174,7 +158,7 @@
  
-   > .toolbarbutton-icon {
-     /* horizontal padding + actual icon width */
--    width: calc(2 * var(--toolbarbutton-padding-inner) + 16px);
--    height: calc(2 * var(--toolbarbutton-padding-inner) + 16px);
-+    width: calc(2 * var(--toolbarbutton-padding-inner) + var(--zen-toolbar-button-size, 16px));
-+    height: calc(2 * var(--toolbarbutton-padding-inner) + var(--zen-toolbar-button-size, 16px));
-   }
+ toolbar .toolbarbutton-1 {
+   /* horizontal padding + actual icon width */
+-  --toolbarbutton-icon-size: calc(2 * var(--toolbarbutton-padding-inner) + 16px);
++  --toolbarbutton-icon-size: calc(2 * var(--toolbarbutton-padding-inner) + var(--zen-toolbar-button-size, 16px));
  
-   > .toolbarbutton-text {
-@@ -216,7 +200,7 @@ toolbar .toolbarbutton-1 {
+   appearance: none;
+   margin: 0;
+@@ -214,7 +198,7 @@ toolbar .toolbarbutton-1 {
       * height as the button icons and the same vertical padding, but as a minimum,
       * because otherwise an increase in text sizes would break things.
       */
@@ -62,7 +60,7 @@ index 94b1a2a841d8fd47a491616d52e5bf544f0c0bf9..9e98266b98c6b66fed26fec12fa3391f
      display: none;
    }
  
-@@ -536,7 +520,7 @@ toolbarbutton.bookmark-item:not(.subviewbutton) {
+@@ -427,7 +411,7 @@ toolbarbutton.bookmark-item:not(.subviewbutton) {
       */
      align-items: stretch;
      > .toolbarbutton-icon {
diff --git a/src/browser/themes/shared/urlbar-searchbar-css.patch b/src/browser/themes/shared/urlbar-css.patch
similarity index 81%
rename from src/browser/themes/shared/urlbar-searchbar-css.patch
rename to src/browser/themes/shared/urlbar-css.patch
index 74b873f46..aa9a81070 100644
--- a/src/browser/themes/shared/urlbar-searchbar-css.patch
+++ b/src/browser/themes/shared/urlbar-css.patch
@@ -1,8 +1,8 @@
-diff --git a/browser/themes/shared/urlbar-searchbar.css b/browser/themes/shared/urlbar-searchbar.css
-index 149f123e26cd79e89432dfeb504ca7218ee04810..7e0e6d981d6c2aa53bc2a76d82d2078419659065 100644
---- a/browser/themes/shared/urlbar-searchbar.css
-+++ b/browser/themes/shared/urlbar-searchbar.css
-@@ -19,8 +19,8 @@
+diff --git a/browser/themes/shared/urlbar.css b/browser/themes/shared/urlbar.css
+index 06183c82e2869290a5fb476c47fb7db92bbef57f..c64cde1eef50d3457fb1c540d95fe3b8aa087294 100644
+--- a/browser/themes/shared/urlbar.css
++++ b/browser/themes/shared/urlbar.css
+@@ -24,8 +24,8 @@
  
    @media not -moz-pref("browser.nova.enabled") {
      --urlbar-basic-component-size: calc(var(--urlbar-height) - 2 * (var(--urlbar-input-container-border-width) + var(--urlbar-input-container-padding)));
@@ -13,7 +13,7 @@ index 149f123e26cd79e89432dfeb504ca7218ee04810..7e0e6d981d6c2aa53bc2a76d82d20784
    }
    @media (max-width: 770px) {
      --urlbar-container-min-width: 240px;
-@@ -127,7 +127,7 @@ toolbar[inactive="true"] .urlbar,
+@@ -143,7 +143,7 @@ toolbar[inactive="true"] .urlbar,
  .urlbar:not([usertyping]) > .urlbar-input-container > .urlbar-go-button,
  .urlbar:not(#searchbar-new, [focused]) > .urlbar-input-container > .urlbar-go-button,
  #urlbar-revert-button-container {
@@ -22,7 +22,7 @@ index 149f123e26cd79e89432dfeb504ca7218ee04810..7e0e6d981d6c2aa53bc2a76d82d20784
  }
  
  /* Document Picture-in-Picture API window */
-@@ -405,6 +405,10 @@ toolbar[inactive="true"] .urlbar,
+@@ -434,6 +434,10 @@ toolbar[inactive="true"] .urlbar,
    .urlbar:not([focused])[textoverflow="left"][domaindir="rtl"] > .urlbar-input-container > .urlbar-input-box > & {
      mask-image: linear-gradient(to right, transparent var(--urlbar-scheme-size), black calc(var(--urlbar-scheme-size) + 3ch));
    }
@@ -33,7 +33,7 @@ index 149f123e26cd79e89432dfeb504ca7218ee04810..7e0e6d981d6c2aa53bc2a76d82d20784
  }
  
  #urlbar-scheme {
-@@ -476,10 +480,15 @@ toolbar[inactive="true"] .urlbar,
+@@ -505,10 +509,15 @@ toolbar[inactive="true"] .urlbar,
    }
  
    .urlbar[breakout][breakout-extend] {
diff --git a/src/build/moz-configure/lto-pgo-configure.patch b/src/build/moz-configure/lto-pgo-configure.patch
index f91a32571..313c9b01c 100644
--- a/src/build/moz-configure/lto-pgo-configure.patch
+++ b/src/build/moz-configure/lto-pgo-configure.patch
@@ -1,5 +1,5 @@
 diff --git a/build/moz.configure/lto-pgo.configure b/build/moz.configure/lto-pgo.configure
-index df2b0bf0081edfdc2c7bccaefc780d2b0c6555ff..53a3b55de7650799e3730372e72ad7b4bb2eea03 100644
+index c72af5ed5f88fc80c810ef626e57a8b991dee514..53a3b55de7650799e3730372e72ad7b4bb2eea03 100644
 --- a/build/moz.configure/lto-pgo.configure
 +++ b/build/moz.configure/lto-pgo.configure
 @@ -234,6 +234,7 @@ def moz_pgo_rust(pgo, profile_use, profile_generate, c_compiler):
@@ -14,7 +14,7 @@ index df2b0bf0081edfdc2c7bccaefc780d2b0c6555ff..53a3b55de7650799e3730372e72ad7b4
      help="Indicate that ld64 is free of symbol aliasing bugs",
  )
  
--imply_option("MOZ_LD64_KNOWN_GOOD", moz_automation)
+-imply_option("MOZ_LD64_KNOWN_GOOD", True, when=moz_automation)
  
  use_fat_lto = cxx_compiler.try_link(
      ldflags=depends(stlport_libs)(
diff --git a/src/external-patches/firefox/bug_2011236.patch b/src/external-patches/firefox/bug_2011236.patch
deleted file mode 100644
index 1a46a9c03..000000000
--- a/src/external-patches/firefox/bug_2011236.patch
+++ /dev/null
@@ -1,168 +0,0 @@
-diff --git a/browser/components/sessionstore/test/browser.toml b/browser/components/sessionstore/test/browser.toml
---- a/browser/components/sessionstore/test/browser.toml
-+++ b/browser/components/sessionstore/test/browser.toml
-@@ -14,10 +14,12 @@
-   "browser_frame_history_c.html",
-   "browser_frame_history_c1.html",
-   "browser_frame_history_c2.html",
-   "browser_formdata_format_sample.html",
-   "browser_sessionHistory_slow.sjs",
-+  "browser_policy_container_sample.html",
-+  "browser_policy_container_sample_frame.html",
-   "browser_scrollPositions_sample.html",
-   "browser_scrollPositions_sample2.html",
-   "browser_scrollPositions_sample_frameset.html",
-   "browser_scrollPositions_readerModeArticle.html",
-   "browser_sessionStorage.html",
-@@ -226,10 +228,12 @@
- ["browser_pinned_tabs.js"]
- skip-if = [
-   "ccov", # Bug 1625525
- ]
- 
-+["browser_policy_container_not_stored.js"]
-+
- ["browser_privatetabs.js"]
- 
- ["browser_purge_domaindata.js"]
- 
- ["browser_purge_shistory.js"]
-diff --git a/browser/components/sessionstore/test/browser_policy_container_not_stored.js b/browser/components/sessionstore/test/browser_policy_container_not_stored.js
-new file mode 100644
---- /dev/null
-+++ b/browser/components/sessionstore/test/browser_policy_container_not_stored.js
-@@ -0,0 +1,51 @@
-+/* This Source Code Form is subject to the terms of the Mozilla Public
-+ * License, v. 2.0. If a copy of the MPL was not distributed with this
-+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-+
-+"use strict";
-+
-+/**
-+ * A session history entry only needs to retain the policy container for loads
-+ * that inherit their policies (about:blank, about:srcdoc, blob:, data:, ...).
-+ * Anything fetched over the network gets its policies from the response again,
-+ * so storing them would only bloat the session store (bug 2011236).
-+ */
-+
-+const TEST_ROOT = getRootDirectory(gTestPath).replace(
-+  "chrome://mochitests/content",
-+  "https://example.com"
-+);
-+const PARENT_URL = TEST_ROOT + "browser_policy_container_sample.html";
-+const FRAME_URL = TEST_ROOT + "browser_policy_container_sample_frame.html";
-+
-+add_task(async function test_policy_container_only_for_inheriting_loads() {
-+  const tab = BrowserTestUtils.addTab(gBrowser, PARENT_URL);
-+  gBrowser.selectedTab = tab;
-+  await promiseBrowserLoaded(tab.linkedBrowser, true, PARENT_URL);
-+  await TabStateFlusher.flush(tab.linkedBrowser);
-+
-+  const state = JSON.parse(ss.getTabState(tab));
-+  const topEntry = state.entries.at(-1);
-+  is(topEntry.url, PARENT_URL, "collected the parent entry");
-+
-+  const children = topEntry.children ?? [];
-+  const networkFrame = children.find(child => child.url === FRAME_URL);
-+  const blankFrame = children.find(child => child.url === "about:blank");
-+
-+  ok(networkFrame, "collected the network-scheme subframe entry");
-+  ok(blankFrame, "collected the about:blank subframe entry");
-+
-+  // The parent has a CSP, so both subframes inherit a policy container onto
-+  // their load state. Only the one that cannot recover it from a response
-+  // should keep it in session history.
-+  ok(
-+    !("policyContainer" in networkFrame),
-+    "https subframe entry does not store a policyContainer"
-+  );
-+  ok(
-+    "policyContainer" in blankFrame,
-+    "about:blank subframe entry still stores its inherited policyContainer"
-+  );
-+
-+  await BrowserTestUtils.removeTab(tab);
-+});
-diff --git a/browser/components/sessionstore/test/browser_policy_container_sample.html b/browser/components/sessionstore/test/browser_policy_container_sample.html
-new file mode 100644
---- /dev/null
-+++ b/browser/components/sessionstore/test/browser_policy_container_sample.html
-@@ -0,0 +1,12 @@
-+<!DOCTYPE html>
-+<html>
-+<head>
-+  <meta charset="utf-8">
-+  <meta http-equiv="Content-Security-Policy" content="default-src * data: blob: 'unsafe-inline'">
-+  <title>policyContainer session store sample</title>
-+</head>
-+<body>
-+  <iframe id="network" src="browser_policy_container_sample_frame.html"></iframe>
-+  <iframe id="blank" src="about:blank"></iframe>
-+</body>
-+</html>
-diff --git a/browser/components/sessionstore/test/browser_policy_container_sample_frame.html b/browser/components/sessionstore/test/browser_policy_container_sample_frame.html
-new file mode 100644
---- /dev/null
-+++ b/browser/components/sessionstore/test/browser_policy_container_sample_frame.html
-@@ -0,0 +1,10 @@
-+<!DOCTYPE html>
-+<html>
-+<head>
-+  <meta charset="utf-8">
-+  <title>policyContainer session store sample frame</title>
-+</head>
-+<body>
-+  frame
-+</body>
-+</html>
-diff --git a/docshell/shistory/SessionHistoryEntry.cpp b/docshell/shistory/SessionHistoryEntry.cpp
---- a/docshell/shistory/SessionHistoryEntry.cpp
-+++ b/docshell/shistory/SessionHistoryEntry.cpp
-@@ -41,10 +41,18 @@
- extern mozilla::LazyLogModule gSHLog;
- 
- namespace mozilla {
- namespace dom {
- 
-+// Only store policy container for loads that can't carry it themselves
-+// (about:blank, about:srcdoc, blob:, data:, ...)
-+// bug 1867137, bug 2011236
-+static nsIPolicyContainer* PolicyContainerToStore(
-+    nsIURI* aURI, nsIPolicyContainer* aPolicyContainer) {
-+  return CSP_ShouldURIInheritCSP(aURI) ? aPolicyContainer : nullptr;
-+}
-+
- SessionHistoryInfo::SessionHistoryInfo(nsDocShellLoadState* aLoadState,
-                                        nsIChannel* aChannel)
-     : mURI(aLoadState->URI()),
-       mOriginalURI(aLoadState->OriginalURI()),
-       mResultPrincipalURI(aLoadState->ResultPrincipalURI()),
-@@ -59,11 +67,12 @@
-       mLoadReplace(aLoadState->LoadReplace()),
-       mHasUserActivation(aLoadState->HasValidUserGestureActivation()),
-       mSharedState(SharedState::Create(
-           aLoadState->TriggeringPrincipal(), aLoadState->PrincipalToInherit(),
-           aLoadState->PartitionedPrincipalToInherit(),
--          aLoadState->PolicyContainer(),
-+          PolicyContainerToStore(aLoadState->URI(),
-+                                 aLoadState->PolicyContainer()),
-           /* FIXME Is this correct? */
-           aLoadState->TypeHint())) {
-   MOZ_DIAGNOSTIC_ASSERT(!mURI->SchemeIs("javascript"));
- 
-   // Pull the upload stream off of the channel instead of the load state, as
-@@ -124,11 +133,12 @@
-   loadInfo->GetPrincipalToInherit(
-       getter_AddRefs(mSharedState.Get()->mPrincipalToInherit));
- 
-   mSharedState.Get()->mPartitionedPrincipalToInherit =
-       aPartitionedPrincipalToInherit;
--  mSharedState.Get()->mPolicyContainer = aPolicyContainer;
-+  mSharedState.Get()->mPolicyContainer =
-+      PolicyContainerToStore(mURI, aPolicyContainer);
-   aChannel->GetContentType(mSharedState.Get()->mContentType);
-   aChannel->GetOriginalURI(getter_AddRefs(mOriginalURI));
- 
-   uint32_t loadFlags;
-   aChannel->GetLoadFlags(&loadFlags);
-
diff --git a/src/external-patches/firefox/bug_2047627_corner_shape_borders.patch b/src/external-patches/firefox/bug_2047627_corner_shape_borders.patch
deleted file mode 100644
index d6d8dfe68..000000000
--- a/src/external-patches/firefox/bug_2047627_corner_shape_borders.patch
+++ /dev/null
@@ -1,1089 +0,0 @@
-diff --git a/gfx/wr/webrender/res/border_shared.glsl b/gfx/wr/webrender/res/border_shared.glsl
-index f385449fa7..313b51bcb0 100644
---- a/gfx/wr/webrender/res/border_shared.glsl
-+++ b/gfx/wr/webrender/res/border_shared.glsl
-@@ -21,6 +21,8 @@ PER_INSTANCE in int aGpuDataAddress;
- PER_INSTANCE in vec4 aClipParams1;
- PER_INSTANCE in vec4 aClipParams2;
- 
-+#endif
-+
- struct BorderInstanceGpuData {
-     vec4 rect;
-     vec4 color0;
-@@ -47,5 +49,3 @@ BorderInstanceGpuData fetch_gpu_data(int index) {
- 
-     return data;
- }
--
--#endif
-diff --git a/gfx/wr/webrender/res/cs_border_segment.glsl b/gfx/wr/webrender/res/cs_border_segment.glsl
-index 6a94117405..56175c4ec2 100644
---- a/gfx/wr/webrender/res/cs_border_segment.glsl
-+++ b/gfx/wr/webrender/res/cs_border_segment.glsl
-@@ -15,10 +15,10 @@ flat varying mediump vec4 vColor11;
- // transition occurs. Used for corners only.
- flat varying highp vec4 vColorLine;
- 
--// x: segment, y: clip mode
-+// x: segment, y: clip mode, z: gpu buffer data address
- // We cast these to/from floats rather than using an ivec due to a driver bug
- // on Adreno 3xx. See bug 1730458.
--flat varying mediump vec2 vSegmentClipMode;
-+flat varying highp vec3 vSegment_ClipMode_DataAddress;
- // x, y: styles, z, w: edge axes
- // We cast these to/from floats rather than using an ivec (and bitshifting)
- // due to a driver bug on Adreno 3xx. See bug 1730458.
-@@ -32,6 +32,7 @@ flat varying highp vec4 vClipCenter_Sign;
- // An outer and inner elliptical radii for border
- // corner clipping.
- flat varying highp vec4 vClipRadii;
-+flat varying highp vec4 vClipOffsets;
- 
- // Reference point for determine edge clip lines.
- flat varying highp vec4 vEdgeReference;
-@@ -181,7 +182,7 @@ void main(void) {
-             break;
-     }
- 
--    vSegmentClipMode = vec2(float(segment), float(clip_mode));
-+    vSegment_ClipMode_DataAddress = vec3(float(segment), float(clip_mode), float(aGpuDataAddress));
-     vStyleEdgeAxis = vec4(float(style0), float(style1), float(edge_axis.x), float(edge_axis.y));
- 
-     vPartialWidths = vec4(data.widths / 3.0, data.widths / 2.0);
-@@ -193,13 +194,23 @@ void main(void) {
-     vec4[2] color1 = get_colors_for_side(data.color1, style1);
-     vColor10 = color1[0];
-     vColor11 = color1[1];
--    vClipCenter_Sign = vec4(outer + clip_sign * data.radii, clip_sign);
-+    vClipCenter_Sign = vec4(outer + clip_sign * (data.radii + data.shape_offset), clip_sign);
-     vClipRadii = vec4(data.radii, max(data.radii - data.widths, 0.0));
-+    vClipOffsets = vec4(0.0);
-     vColorLine = vec4(outer, data.widths.y * -clip_sign.y, data.widths.x * clip_sign.x);
-     vEdgeReference = vec4(edge_reference, edge_reference + data.widths);
-     vClipParams1 = aClipParams1;
-     vClipParams2 = aClipParams2;
- 
-+    if (data.shape != 1.0)
-+    {
-+        vec2 reference_radii = (data.radii == vec2(0.0)) ? vec2(0.0) : data.radii + data.inset;
-+        vec4 contour1 = compute_contoured_superellipse(reference_radii, data.shape, data.inset);
-+        vec4 contour2 = compute_contoured_superellipse(reference_radii, data.shape, data.inset + data.widths);
-+        vClipOffsets = vec4(contour1.xy, contour2.xy);
-+        vClipRadii = vec4(contour1.zw, contour2.zw);
-+    }
-+
-     // For the case of dot and dash clips, optimize the number of pixels that
-     // are hit to just include the dot itself.
-     if (clip_mode == CLIP_DOT) {
-@@ -231,6 +242,7 @@ void main(void) {
- 
- #ifdef WR_FRAGMENT_SHADER
- vec4 evaluate_color_for_style_in_corner(
-+    BorderInstanceGpuData data,
-     vec2 clip_relative_pos,
-     int style,
-     vec4 color0,
-@@ -246,24 +258,61 @@ vec4 evaluate_color_for_style_in_corner(
-             // also 0.67 of the radii. Use these to form a
-             // SDF subtraction which will clip out the inside
-             // third of the rounded edge.
--            float d_radii_a = distance_to_ellipse(
--                clip_relative_pos,
--                clip_radii.xy - vPartialWidths.xy
--            );
--            float d_radii_b = distance_to_ellipse(
--                clip_relative_pos,
--                clip_radii.xy - 2.0 * vPartialWidths.xy
--            );
-+            float d_radii_a;
-+            float d_radii_b;
-+            if (data.shape == 1.0) {
-+                d_radii_a = distance_to_ellipse(
-+                    clip_relative_pos,
-+                    clip_radii.xy - vPartialWidths.xy
-+                );
-+                d_radii_b = distance_to_ellipse(
-+                    clip_relative_pos,
-+                    clip_radii.xy - 2.0 * vPartialWidths.xy
-+                );
-+            } else {
-+                d_radii_a = distance_to_superellipse(
-+                    clip_relative_pos - mix(vClipOffsets.xy, vClipOffsets.zw, 1.0 / 3.0),
-+                    mix(clip_radii.xy, clip_radii.zw, 1.0 / 3.0),
-+                    data.shape
-+                );
-+                d_radii_b = distance_to_superellipse(
-+                    clip_relative_pos - mix(vClipOffsets.xy, vClipOffsets.zw, 2.0 / 3.0),
-+                    mix(clip_radii.xy, clip_radii.zw, 2.0 / 3.0),
-+                    data.shape
-+                );
-+
-+                // Clamp to the middle of the adjacent borders
-+                vec2 included_region_a = data.radii - vPartialWidths.xy - clip_relative_pos;
-+                d_radii_a = max(d_radii_a, -min(included_region_a.x, included_region_a.y));
-+
-+                vec2 included_region_b = data.radii - 2.0 * vPartialWidths.xy - clip_relative_pos;
-+                d_radii_b = max(d_radii_b, -min(included_region_b.x, included_region_b.y));
-+            }
-+
-             float d = min(-d_radii_a, d_radii_b);
-+
-             color0 *= distance_aa(aa_range, d);
-             break;
-         }
-         case BORDER_STYLE_GROOVE:
-         case BORDER_STYLE_RIDGE: {
--            float d = distance_to_ellipse(
--                clip_relative_pos,
--                clip_radii.xy - vPartialWidths.zw
--            );
-+            float d;
-+            if (data.shape == 1.0) {
-+                d = distance_to_ellipse(
-+                    clip_relative_pos,
-+                    clip_radii.xy - vPartialWidths.zw
-+                );
-+            } else {
-+                d = distance_to_superellipse(
-+                    clip_relative_pos - mix(vClipOffsets.xy, vClipOffsets.zw, 0.5),
-+                    mix(clip_radii.xy, clip_radii.zw, 0.5),
-+                    data.shape
-+                );
-+
-+                // Clamp to the middle of the adjacent borders
-+                vec2 included_region = data.radii - vPartialWidths.zw - clip_relative_pos;
-+                d = max(d, -min(included_region.x, included_region.y));
-+            }
-             float alpha = distance_aa(aa_range, d);
-             float swizzled_factor;
-             switch (segment) {
-@@ -328,11 +377,14 @@ void main(void) {
-     float aa_range = compute_aa_range(vPos);
-     vec4 color0, color1;
- 
--    int segment = int(vSegmentClipMode.x);
--    int clip_mode = int(vSegmentClipMode.y);
-+    int segment = int(vSegment_ClipMode_DataAddress.x);
-+    int clip_mode = int(vSegment_ClipMode_DataAddress.y);
-+    int data_address = int(vSegment_ClipMode_DataAddress.z);
-     ivec2 style = ivec2(int(vStyleEdgeAxis.x), int(vStyleEdgeAxis.y));
-     ivec2 edge_axis = ivec2(int(vStyleEdgeAxis.z), int(vStyleEdgeAxis.w));
- 
-+    BorderInstanceGpuData data = fetch_gpu_data(data_address);
-+
-     float mix_factor = 0.0;
-     if (edge_axis.x != edge_axis.y) {
-         float d_line = distance_to_line(vColorLine.xy, vColorLine.zw, vPos);
-@@ -382,12 +434,27 @@ void main(void) {
-     }
- 
-     if (in_clip_region) {
--        float d_radii_a = distance_to_ellipse(clip_relative_pos, vClipRadii.xy);
--        float d_radii_b = distance_to_ellipse(clip_relative_pos, vClipRadii.zw);
-+        float d_radii_a;
-+        float d_radii_b;
-+
-+        if (data.shape == 1.0) {
-+            d_radii_a = distance_to_ellipse(clip_relative_pos, vClipRadii.xy);
-+            d_radii_b = distance_to_ellipse(clip_relative_pos, vClipRadii.zw);
-+        } else {
-+            clip_relative_pos = abs(clip_relative_pos) - data.shape_offset;
-+            d_radii_a = distance_to_superellipse(clip_relative_pos - vClipOffsets.xy, vClipRadii.xy, data.shape);
-+            d_radii_b = distance_to_superellipse(clip_relative_pos - vClipOffsets.zw, vClipRadii.zw, data.shape);
-+
-+            // exclude the straight border part from the subtracted region
-+            vec2 included_region = data.radii - data.widths - clip_relative_pos;
-+            d_radii_b = max(d_radii_b, -min(included_region.x, included_region.y));
-+        }
-+
-         float d_radii = max(d_radii_a, -d_radii_b);
-         d = max(d, d_radii);
--
-+        
-         color0 = evaluate_color_for_style_in_corner(
-+            data,
-             clip_relative_pos,
-             style.x,
-             vColor00,
-@@ -398,6 +465,7 @@ void main(void) {
-             aa_range
-         );
-         color1 = evaluate_color_for_style_in_corner(
-+            data,
-             clip_relative_pos,
-             style.y,
-             vColor10,
-diff --git a/gfx/wr/webrender/res/cs_border_solid.glsl b/gfx/wr/webrender/res/cs_border_solid.glsl
-index 90584346a4..a3ff0e887e 100644
---- a/gfx/wr/webrender/res/cs_border_solid.glsl
-+++ b/gfx/wr/webrender/res/cs_border_solid.glsl
-@@ -8,6 +8,10 @@
- #define MIX_AA 1
- #define MIX_NO_AA 2
- 
-+// Address of border data in the GPU Buffer.
-+// Packed in to a vector to work around bug 1630356.
-+flat varying highp ivec2 vGpuDataAddress;
-+
- // For edges, the colors are the same. For corners, these
- // are the colors of each edge making up the corner.
- flat varying mediump vec4 vColor0;
-@@ -29,6 +33,7 @@ flat varying highp vec4 vClipCenter_Sign;
- // An outer and inner elliptical radii for border
- // corner clipping.
- flat varying highp vec4 vClipRadii;
-+flat varying highp vec4 vClipOffsets;
- 
- // Position, scale, and radii of horizontally and vertically adjacent corner clips.
- flat varying highp vec4 vHorizontalClipCenter_Sign;
-@@ -68,6 +73,7 @@ vec2 get_outer_corner_scale(int segment) {
- 
- void main(void) {
-     BorderInstanceGpuData data = fetch_gpu_data(aGpuDataAddress);
-+    vGpuDataAddress.x = aGpuDataAddress;
- 
-     int segment = aFlags & 0xff;
-     bool do_aa = ((aFlags >> 24) & 0xf0) != 0;
-@@ -96,10 +102,20 @@ void main(void) {
- 
-     vColor0 = data.color0;
-     vColor1 = data.color1;
--    vClipCenter_Sign = vec4(outer + clip_sign * data.radii, clip_sign);
-+    vClipCenter_Sign = vec4(outer + clip_sign * (data.radii + data.shape_offset), clip_sign);
-     vClipRadii = vec4(data.radii, max(data.radii - data.widths, 0.0));
-+    vClipOffsets = vec4(0.0);
-     vColorLine = vec4(outer, data.widths.y * -clip_sign.y, data.widths.x * clip_sign.x);
- 
-+    if (data.shape != 1.0)
-+    {
-+        vec2 reference_radii = (data.radii == vec2(0.0)) ? vec2(0.0) : data.radii + data.inset;
-+        vec4 contour1 = compute_contoured_superellipse(reference_radii, data.shape, data.inset);
-+        vec4 contour2 = compute_contoured_superellipse(reference_radii, data.shape, data.inset + data.widths);
-+        vClipOffsets = vec4(contour1.xy, contour2.xy);
-+        vClipRadii = vec4(contour1.zw, contour2.zw);
-+    }
-+
-     vec2 horizontal_clip_sign = vec2(-clip_sign.x, clip_sign.y);
-     vHorizontalClipCenter_Sign = vec4(aClipParams1.xy +
-                                       horizontal_clip_sign * aClipParams1.zw,
-@@ -118,6 +134,8 @@ void main(void) {
- 
- #ifdef WR_FRAGMENT_SHADER
- void main(void) {
-+    BorderInstanceGpuData data = fetch_gpu_data(vGpuDataAddress.x);
-+
-     float aa_range = compute_aa_range(vPos);
-     bool do_aa = vMixColors.x != MIX_NO_AA;
- 
-@@ -137,8 +155,22 @@ void main(void) {
- 
-     float d = -1.0;
-     if (in_clip_region) {
--        float d_radii_a = distance_to_ellipse(clip_relative_pos, vClipRadii.xy);
--        float d_radii_b = distance_to_ellipse(clip_relative_pos, vClipRadii.zw);
-+        float d_radii_a;
-+        float d_radii_b;
-+
-+        if (data.shape == 1.0) {
-+            d_radii_a = distance_to_ellipse(clip_relative_pos, vClipRadii.xy);
-+            d_radii_b = distance_to_ellipse(clip_relative_pos, vClipRadii.zw);
-+        } else {
-+            clip_relative_pos = abs(clip_relative_pos) - data.shape_offset;
-+            d_radii_a = distance_to_superellipse(clip_relative_pos - vClipOffsets.xy, vClipRadii.xy, data.shape);
-+            d_radii_b = distance_to_superellipse(clip_relative_pos - vClipOffsets.zw, vClipRadii.zw, data.shape);
-+
-+            // exclude the straight border part from the subtracted region
-+            vec2 included_region = data.radii - data.widths - clip_relative_pos;
-+            d_radii_b = max(d_radii_b, -min(included_region.x, included_region.y));
-+        }
-+
-         d = max(d_radii_a, -d_radii_b);
-     }
- 
-diff --git a/gfx/wr/webrender/res/ellipse.glsl b/gfx/wr/webrender/res/ellipse.glsl
-index cb7d5d89af..7ce1bcacb4 100644
---- a/gfx/wr/webrender/res/ellipse.glsl
-+++ b/gfx/wr/webrender/res/ellipse.glsl
-@@ -27,9 +27,27 @@ float compute_superellipse_half_corner(float shape) {
-     float n = exp2(shape);
-     float convex_half_corner = pow(0.5, 1.0 / n);
- 
-+    // Ensure the curve tends towards 0.75 (which will produce axis-aligned
-+    // normals in compute_superellipse_normals()) when shape goes to 1 (round).
-+    // This makes the curve continuous from subellipses (shape < 1) to
-+    // superellipses (shape > 1).
-+    // The original half corner (above) goes to 0.5^0.5 = sqrt(2) / 2 ~= 0.707,
-+    // so the delta is about 6% at maximum.
-+    const float delta = 0.04289321881345243; // = 0.75 - pow(0.5, 0.5)
-+    float falloff = shape * shape; // quadratic falloff
-+    convex_half_corner += delta * falloff;
-+
-     return convex_half_corner;
- }
- 
-+// Super cheap approximation of the function above: the delta with quadratic
-+// falloff actually makes it almost locally linear for shape values between
-+// zero and one.
-+float compute_superellipse_half_corner_approx(float shape) {
-+    shape = min(1.0, abs(shape));
-+    return 0.25 * shape + 0.5;
-+}
-+
- #if 0
- 
- // Alternate method to find the normals of a superellipse
-@@ -118,8 +136,15 @@ float compute_superellipse_half_corner(float shape) {
- // dy/dx = -b / a * qx * (1 - x0 / a * qx)^((1-n) / n) # Careful, exponent flipped
- //
- vec4 compute_superellipse_normals(vec2 radii, float shape) {
--    float n = exp2(abs(shape));
--    float q = pow(0.05, n - 1.0);
-+    shape = min(1.0, abs(shape));
-+
-+    float n = exp2(shape);
-+
-+    // The damping factor makes q go to zero when shape approches one,
-+    // ensuring continuity with higher-order superellipses (for shapes
-+    // of 1 and above, the normals should always be axis-aligned)
-+    float damping_factor = (1.0 - shape * shape);
-+    float q = pow(0.05 * damping_factor, n - 1.0);
- 
-     // x: dy/dx at (0.05 * radii.x, radii.y)
-     // y: dx/dy at (radii.x, 0.05 * radii.y)
-@@ -137,8 +162,7 @@ vec4 compute_superellipse_normals(vec2 radii, float shape) {
- //
- // Returns start and end normals in (x, y) and (z, w) respectively
- vec4 compute_superellipse_normals(vec2 radii, float shape) {
--
--    float convex_half_corner = compute_superellipse_half_corner(shape);
-+    float convex_half_corner = compute_superellipse_half_corner_approx(shape);
-     vec2 tangent = vec2(0.5 - 2.0 * convex_half_corner, 2.0 * convex_half_corner - 1.5);
- 
-     // Avoid dividing by zero
-diff --git a/gfx/wr/wrench/reftests/border/border-shape-2.yaml b/gfx/wr/wrench/reftests/border/border-shape-2.yaml
-new file mode 100644
-index 0000000000..44f12d74f3
---- /dev/null
-+++ b/gfx/wr/wrench/reftests/border/border-shape-2.yaml
-@@ -0,0 +1,51 @@
-+---
-+root:
-+  items:
-+    - type: stacking-context
-+      bounds: [0, 0, 480, 320 ]
-+      items:
-+        - type: rect
-+          bounds: [0, 0, 480, 320 ]
-+          color: black
-+        - type: border
-+          bounds: [ 20, 20, 120, 120 ]
-+          width: 16
-+          border-type: normal
-+          style: solid
-+          color: white
-+          radius: [ 4, 4, 60, 40, 26.0, 2.0, 6.0, 9.0 ]
-+        - type: border
-+          bounds: [ 180, 20, 120, 120 ]
-+          width: [16, 6.4, 12.8, 4]
-+          border-type: normal
-+          style: solid
-+          color: white
-+          radius: [ 24, 24, 24, 24, 2.0, 2.0, 2.0, 2.0 ]
-+        - type: border
-+          bounds: [ 340, 20, 120, 120 ]
-+          width: [3.2, 6.4, 12.8, 4]
-+          border-type: normal
-+          style: solid
-+          color: white
-+          radius: [ 16, 16, 16, 16, 2.0, -2.0, 0.0, 2.0 ]
-+        - type: border
-+          bounds: [ 20, 180, 120, 120 ]
-+          width: 16
-+          border-type: normal
-+          style: double
-+          color: white
-+          radius: [ 4, 4, 4, 4, 2.0, 2.0, 2.0, 2.0 ]
-+        - type: border
-+          bounds: [ 180, 180, 120, 120 ]
-+          width: 16
-+          border-type: normal
-+          style: double
-+          color: white
-+          radius: [ 8, 8, 8, 8, 2.0, 2.0, 2.0, 2.0 ]
-+        - type: border
-+          bounds: [ 340, 180, 120, 120 ]
-+          width: [16, 8, 3, 6.4]
-+          border-type: normal
-+          style: double
-+          color: white
-+          radius: [ 16, 16, 16, 16, 2.0, -2.0, 2.0, 2.0 ]
-diff --git a/gfx/wr/wrench/reftests/border/border-shape-3.yaml b/gfx/wr/wrench/reftests/border/border-shape-3.yaml
-new file mode 100644
-index 0000000000..5085c083dc
---- /dev/null
-+++ b/gfx/wr/wrench/reftests/border/border-shape-3.yaml
-@@ -0,0 +1,16 @@
-+---
-+root:
-+  items:
-+    - type: stacking-context
-+      bounds: [0, 0, 400, 400 ]
-+      items:
-+        - type: rect
-+          bounds: [0, 0, 400, 400 ]
-+          color: black
-+        - type: border
-+          bounds: [ 50, 50, 300, 300 ]
-+          width: [40, 2, 20, 50]
-+          border-type: normal
-+          style: solid
-+          color: white
-+          radius: [ 60, 30, [100, 50], [100, 50], 0.2, 0.0, -Inf, -0.7 ]
-diff --git a/gfx/wr/wrench/reftests/border/border-shape-4.yaml b/gfx/wr/wrench/reftests/border/border-shape-4.yaml
-new file mode 100644
-index 0000000000..27c9b2fd9d
---- /dev/null
-+++ b/gfx/wr/wrench/reftests/border/border-shape-4.yaml
-@@ -0,0 +1,25 @@
-+---
-+root:
-+  items:
-+    - type: stacking-context
-+      bounds: [0, 0, 400, 300 ]
-+      items:
-+        - type: rect
-+          bounds: [0, 0, 400, 300 ]
-+          color: black
-+        - type: clip
-+          id: 2
-+          complex:
-+            - rect: [ 50, 50, 300, 200 ]
-+              radius: [ 0, 30, 60, 0, 0.0, 0.0, 0.0, 0.0 ]
-+        - type: rect
-+          clip-chain: [2]
-+          bounds: [ 50, 50, 300, 200 ]
-+          color: white
-+        - type: border
-+          bounds: [ 50, 50, 300, 200 ]
-+          width: [0, 0, 50, 50]
-+          border-type: normal
-+          style: solid
-+          color: [[0, 1, 0, 0.2], [1, 0, 0, 0.3], [0, 0, 1, 0.2], [1, 1, 0, 0.3]]
-+          radius: [ 0, 30, 60, 0, 0.0, 0.0, 0.0, 0.0 ]
-diff --git a/gfx/wr/wrench/reftests/border/border-shape-inset.yaml b/gfx/wr/wrench/reftests/border/border-shape-inset.yaml
-new file mode 100644
-index 0000000000..4b6e51ee3e
---- /dev/null
-+++ b/gfx/wr/wrench/reftests/border/border-shape-inset.yaml
-@@ -0,0 +1,42 @@
-+---
-+root:
-+  items:
-+    - type: stacking-context
-+      bounds: [ 0, 0, 320, 320 ]
-+      items:
-+        - type: rect
-+          bounds: [ 0, 0, 320, 320 ]
-+          color: black
-+        - type: border
-+          bounds: [ 20, 20, 280, 280 ]
-+          width: [ 16, 2, 8, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: white
-+          radius: [ 24, 12, 120, [80, 20], 0.2, 0.0, -Inf, -0.7 ]
-+          inset: [ 0, 0, 0, 0 ]
-+        - type: border
-+          bounds: [ 12, 12, 296, 296 ]
-+          width: [ 2, 2, 2, 2 ]
-+          border-type: normal
-+          style: solid
-+          color: yellow
-+          radius: [ 32, 20, 128, [88, 28], 0.2, 0.0, -Inf, -0.7 ]
-+          inset: [ -8, -8, -8, -8 ]
-+        - type: border
-+          bounds: [ 24.8, 40, 251.2, 248 ]
-+          width: [ 2, 2, 2, 2 ]
-+          border-type: normal
-+          style: solid
-+          color: magenta
-+          radius: {
-+            top-left: [19.2, 4],
-+            top-right: [0, 0],
-+            bottom-left: [115, 108],
-+            bottom-right: [56, 8],
-+            shape-top-left: 0.2,
-+            shape-top-right: 0.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: -0.7,
-+          }
-+          inset: [ 20, 24, 12, 4.8 ]
-diff --git a/gfx/wr/wrench/reftests/border/border-shape.yaml b/gfx/wr/wrench/reftests/border/border-shape.yaml
-new file mode 100644
-index 0000000000..c0ac275110
---- /dev/null
-+++ b/gfx/wr/wrench/reftests/border/border-shape.yaml
-@@ -0,0 +1,419 @@
-+---
-+root:
-+  items:
-+    - type: stacking-context
-+      bounds: [0, 0, 1000, 1000]
-+      items:
-+        - type: border
-+          bounds: [ 10, 10, 100, 100 ]
-+          width: [ 1, 1, 1, 1 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 20],
-+            top-right: [10, 10],
-+            bottom-left: [25, 25],
-+            bottom-right: [0, 0],
-+          }
-+        - type: border
-+          bounds: [ 120, 10, 100, 100 ]
-+          width: [ 2, 2, 2, 2 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 20],
-+            top-right: [10, 10],
-+            bottom-left: [25, 25],
-+            bottom-right: [0, 0],
-+            shape-top-left: 2,
-+            shape-top-right: -1.5,
-+            shape-bottom-left: 0,
-+            shape-bottom-right: +Inf,
-+          }
-+        - type: border
-+          bounds: [ 230, 10, 100, 100 ]
-+          width: [ 3, 3, 3, 3 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 20],
-+            top-right: [10, 10],
-+            bottom-left: [25, 25],
-+            bottom-right: [0, 0],
-+            shape-top-left: 2,
-+            shape-top-right: -1.5,
-+            shape-bottom-left: 0,
-+            shape-bottom-right: +Inf,
-+          }
-+        - type: border
-+          bounds: [ 340, 10, 100, 100 ]
-+          width: [ 5, 5, 5, 5 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 20],
-+            top-right: [10, 10],
-+            bottom-left: [25, 25],
-+            bottom-right: [0, 0],
-+            shape-top-left: 2,
-+            shape-top-right: -1.5,
-+            shape-bottom-left: 0,
-+            shape-bottom-right: +Inf,
-+          }
-+        - type: border
-+          bounds: [ 450, 10, 100, 100 ]
-+          width: [ 5, 5, 5, 5 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 20],
-+            top-right: [10, 10],
-+            bottom-left: [25, 25],
-+            bottom-right: [0, 0],
-+            shape-top-left: 2,
-+            shape-top-right: -1.5,
-+            shape-bottom-left: 0,
-+            shape-bottom-right: +Inf,
-+          }
-+        - type: border
-+          bounds: [ 560, 10, 100, 100 ]
-+          width: [ 10, 10, 10, 10 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 20],
-+            top-right: [10, 10],
-+            bottom-left: [25, 25],
-+            bottom-right: [0, 0],
-+            shape-top-left: 2,
-+            shape-top-right: -1.5,
-+            shape-bottom-left: 0,
-+            shape-bottom-right: +Inf,
-+          }
-+
-+        - type: border
-+          bounds: [ 10, 120, 100, 100 ]
-+          width: 10
-+          border-type: normal
-+          style: inset
-+          color: [ red, green, blue, black ]
-+        - type: border
-+          bounds: [ 120, 120, 100, 100 ]
-+          width: 10
-+          border-type: normal
-+          style: outset
-+          color: [ red, green, blue, black ]
-+        - type: border
-+          bounds: [ 230, 120, 100, 100 ]
-+          width: 10
-+          border-type: normal
-+          style: inset
-+          color: [ red, green, blue, black ]
-+          radius: [10, 0.5]
-+        - type: border
-+          bounds: [ 340, 120, 100, 100 ]
-+          width: 10
-+          border-type: normal
-+          style: outset
-+          color: [ red, green, blue, black ]
-+          radius: [20, -0.3]
-+        - type: border
-+          bounds: [ 450, 120, 100, 100 ]
-+          width: 10
-+          border-type: normal
-+          style: outset
-+          color: [ red, green, blue, black ]
-+          radius: [35, 2.2]
-+        - type: border
-+          bounds: [ 560, 120, 100, 100 ]
-+          width: 10
-+          border-type: normal
-+          style: outset
-+          color: [ red, green, blue, black ]
-+          radius: [50, -2.6]
-+
-+        - type: border
-+          bounds: [ 10, 230, 100, 100 ]
-+          width: [ 1, 1, 1, 1 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 120, 230, 100, 100 ]
-+          width: [ 2, 2, 2, 2 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 230, 230, 100, 100 ]
-+          width: [ 3, 3, 3, 3 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 340, 230, 100, 100 ]
-+          width: [ 5, 5, 5, 5 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 450, 230, 100, 100 ]
-+          width: [ 5, 5, 5, 5 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 560, 230, 100, 100 ]
-+          width: [ 10, 10, 10, 10 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+
-+        - type: border
-+          bounds: [ 10, 340, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 120, 340, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 230, 340, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 340, 340, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 450, 340, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+        - type: border
-+          bounds: [ 560, 340, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: {
-+            top-left: [20, 40],
-+            top-right: [30, 10],
-+            bottom-left: [21, 7],
-+            bottom-right: [0, 5],
-+            shape-top-left: -1.2,
-+            shape-top-right: 4.0,
-+            shape-bottom-left: -Inf,
-+            shape-bottom-right: 8.0,
-+          }
-+
-+        - type: border
-+          bounds: [ 10, 450, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: [0, -Inf]
-+        - type: border
-+          bounds: [ 120, 450, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: [10, -Inf]
-+        - type: border
-+          bounds: [ 230, 450, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: [20, -Inf]
-+        - type: border
-+          bounds: [ 340, 450, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: [30, -2.3]
-+        - type: border
-+          bounds: [ 450, 450, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: [40, -2.3]
-+        - type: border
-+          bounds: [ 560, 450, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: solid
-+          color: [ red, green, blue, black ]
-+          radius: [50, -2.3]
-+
-+        - type: border
-+          bounds: [ 10, 560, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: [0, -2.3]
-+        - type: border
-+          bounds: [ 120, 560, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: [10, -2.3]
-+        - type: border
-+          bounds: [ 230, 560, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: [20, -2.3]
-+        - type: border
-+          bounds: [ 340, 560, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: [30, -2.3]
-+        - type: border
-+          bounds: [ 450, 560, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: [40, -2.3]
-+        - type: border
-+          bounds: [ 560, 560, 100, 100 ]
-+          width: [ 20, 20, 20, 20 ]
-+          border-type: normal
-+          style: double
-+          color: [ red, green, blue, black ]
-+          radius: [50, -2.3]
-diff --git a/gfx/wr/wrench/reftests/border/reftest.list b/gfx/wr/wrench/reftests/border/reftest.list
-index 98550ba96a..8813005879 100644
---- a/gfx/wr/wrench/reftests/border/reftest.list
-+++ b/gfx/wr/wrench/reftests/border/reftest.list
-@@ -39,3 +39,8 @@ scale(*) != small-inset-outset.yaml small-inset-outset-notref.yaml
- fuzzy(1,90) == no-aa.yaml green-square.yaml
- fuzzy(1,20) skip_on(android,device) == border-double-1px.yaml border-double-1px-ref.yaml  # Fails on Pixel2
- == max-scale.yaml max-scale-ref.yaml
-+platform(linux,mac) == border-shape.yaml border-shape.png
-+platform(linux,mac) == border-shape-2.yaml border-shape-2.png
-+platform(linux,mac) == border-shape-3.yaml border-shape-3.png
-+platform(linux,mac) == border-shape-4.yaml border-shape-4.png
-+platform(linux,mac) == border-shape-inset.yaml border-shape-inset.png
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-bevel.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-bevel.html.ini
-index 48f1f399ff..64de30993d 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-bevel.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-bevel.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-bevel.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch-mixed.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch-mixed.html.ini
-index e8f92f3417..0cef33e8c4 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch-mixed.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch-mixed.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-notch-mixed.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch.html.ini
-index e69fb19cc6..9cd5ad23a6 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-notch.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-notch.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-scoop.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-scoop.html.ini
-index b8df36dfff..bebaeb9706 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-scoop.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-scoop.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-scoop.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-mixed.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-mixed.html.ini
-index d33e0df628..e829d53044 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-mixed.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-mixed.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-square-notch-mixed.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-superellipse.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-superellipse.html.ini
-index d66f06741d..12d5bac673 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-superellipse.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square-notch-superellipse.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-square-notch-superellipse.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square.html.ini
-index e9b1a330d2..5aca5449b0 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-square.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-square.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-bevel.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-bevel.html.ini
-index 1a106e3e3c..f175e3fb97 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-bevel.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-bevel.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-superellipse-bevel.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-100.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-100.html.ini
-index df13a251a0..6a32def3ac 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-100.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-100.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-superellipse-negative-100.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-inf.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-inf.html.ini
-index c6a7827768..4c2ad71472 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-inf.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-negative-inf.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-superellipse-negative-inf.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-scoop.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-scoop.html.ini
-index f3e23852d0..fc98f5a2f2 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-scoop.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/corner-shape-superellipse-scoop.html.ini
-@@ -1,2 +1,3 @@
- [corner-shape-superellipse-scoop.html]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
-diff --git a/testing/web-platform/meta/css/css-borders/corner-shape/render-corner-shape.html.ini b/testing/web-platform/meta/css/css-borders/corner-shape/render-corner-shape.html.ini
-index 84c9fe0339..6c121825bb 100644
---- a/testing/web-platform/meta/css/css-borders/corner-shape/render-corner-shape.html.ini
-+++ b/testing/web-platform/meta/css/css-borders/corner-shape/render-corner-shape.html.ini
-@@ -7,7 +7,8 @@
-     if useDrawSnapshot: FAIL
- 
- [render-corner-shape.html?border-top-left-radius=50%&corner-shape=0.7&border-left-width=30&border-top-width=30]
--  expected: FAIL
-+  expected:
-+    if useDrawSnapshot: FAIL
- 
- [render-corner-shape.html?corner-shape=-2&border-radius=20%&border-width=20]
-   expected:
-diff --git a/widget/ThemeDrawing.cpp b/widget/ThemeDrawing.cpp
-index c2550d9c2d..ec7aa4bb1c 100644
---- a/widget/ThemeDrawing.cpp
-+++ b/widget/ThemeDrawing.cpp
-@@ -98,7 +98,11 @@ void ThemeDrawing::PaintRoundedRectWithRadius(
-       wr::BorderRadius radii = {{backgroundRadius, backgroundRadius},
-                                 {backgroundRadius, backgroundRadius},
-                                 {backgroundRadius, backgroundRadius},
--                                {backgroundRadius, backgroundRadius}};
-+                                {backgroundRadius, backgroundRadius},
-+                                1.0f,
-+                                1.0f,
-+                                1.0f,
-+                                1.0f};
-       aWrData.mBuilder.PushBorder(backgroundRect, clip, kBackfaceIsVisible,
-                                   widths, {sides, 4}, radii);
-     }
diff --git a/src/external-patches/firefox/bug_2063169/D319577.patch b/src/external-patches/firefox/bug_2063169/D319577.patch
deleted file mode 100644
index ac4efedf1..000000000
--- a/src/external-patches/firefox/bug_2063169/D319577.patch
+++ /dev/null
@@ -1,558 +0,0 @@
-diff --git a/gfx/wr/webrender/res/ps_quad_mask.glsl b/gfx/wr/webrender/res/ps_quad_mask.glsl
---- a/gfx/wr/webrender/res/ps_quad_mask.glsl
-+++ b/gfx/wr/webrender/res/ps_quad_mask.glsl
-@@ -19,12 +19,14 @@
- // We pack 4 vec3 clip planes into 3 vec4 to save a varying slot.
- flat varying highp vec4 vClipPlane_A;
- flat varying highp vec4 vClipPlane_B;
- flat varying highp vec4 vClipPlane_C;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
- flat varying highp vec4 vClipShape;
- flat varying highp vec4 vClipClampedInset;
-+#endif
- 
- #endif
- flat varying highp vec2 vClipMode;
- 
- #ifdef WR_VERTEX_SHADER
-@@ -40,12 +42,14 @@
-     vec4 radii;
- #else
-     vec4 radii_top;
-     vec4 radii_bottom;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vec4 shape;
-     vec4 inset;
-+#endif
- #endif
-     float mode;
-     int space;
- };
- 
-@@ -58,22 +62,29 @@
-     vec4 texels[3] = fetch_from_gpu_buffer_3f(index);
-     clip.rect = RectWithEndpoint(texels[0].xy, texels[0].zw);
-     clip.radii = texels[1];
-     clip.mode = texels[2].x;
- #else
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vec4 texels[6] = fetch_from_gpu_buffer_6f(index);
-+#else
-+    vec4 texels[4] = fetch_from_gpu_buffer_4f(index);
-+#endif
-     clip.rect = RectWithEndpoint(texels[0].xy, texels[0].zw);
-     clip.radii_top = texels[1];
-     clip.radii_bottom = texels[2];
-     clip.mode = texels[3].x;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     clip.shape = texels[4];
-     clip.inset = texels[5];
-+#endif
- #endif
- 
-     return clip;
- }
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
- vec4 precalc_corner(vec2 center, vec2 radii, vec2 inset, vec2 clip_sign, float k) {
-     if (k == 1.0) {
-         // round/ellipse corner, precalc the ellipse parameters
-         return vec4(center, inverse_radii_squared(radii));
-     } else {
-@@ -85,10 +96,11 @@
-             radii = offset_radii.zw;
-         }
-         return vec4(center, inverse_radii(radii));
-     }
- }
-+#endif
- 
- void pattern_vertex(PrimitiveInfo prim_info) {
- 
-     Clip clip = fetch_clip(aClipData.y);
-     Transform clip_transform = fetch_transform(aClipData.x);
-@@ -121,10 +133,11 @@
-     vec2 r_tl = clip.radii_top.xy;
-     vec2 r_tr = clip.radii_top.zw;
-     vec2 r_br = clip.radii_bottom.zw;
-     vec2 r_bl = clip.radii_bottom.xy;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vClipCenter_Radius_TL = precalc_corner(clip.rect.p0 + r_tl,
-                                            r_tl,
-                                            clip.inset.wx,
-                                            vec2(-1.0, -1.0),
-                                            clip.shape.x);
-@@ -146,10 +159,25 @@
-                                                 clip.rect.p1.y - r_bl.y),
-                                            r_bl,
-                                            clip.inset.wz,
-                                            vec2(-1.0, 1.0),
-                                            clip.shape.w);
-+#else
-+    vClipCenter_Radius_TL = vec4(clip.rect.p0 + r_tl,
-+                                 inverse_radii_squared(r_tl));
-+
-+    vClipCenter_Radius_TR = vec4(clip.rect.p1.x - r_tr.x,
-+                                 clip.rect.p0.y + r_tr.y,
-+                                 inverse_radii_squared(r_tr));
-+
-+    vClipCenter_Radius_BR = vec4(clip.rect.p1 - r_br,
-+                                 inverse_radii_squared(r_br));
-+
-+    vClipCenter_Radius_BL = vec4(clip.rect.p0.x + r_bl.x,
-+                                 clip.rect.p1.y - r_bl.y,
-+                                 inverse_radii_squared(r_bl));
-+#endif
- 
-     // We need to know the half-spaces of the corners separate from the center
-     // and radius. We compute a point that falls on the diagonal (which is just
-     // an inner vertex pushed out along one axis, but not on both) to get the
-     // plane offset of the half-space. We also compute the direction vector of
-@@ -170,13 +198,15 @@
- 
-     vClipPlane_A = vec4(tl.x, tl.y, tl.z, tr.x);
-     vClipPlane_B = vec4(tr.y, tr.z, br.x, br.y);
-     vClipPlane_C = vec4(br.z, bl.x, bl.y, bl.z);
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vClipShape = clip.shape;
-     vClipClampedInset = min(clip.inset, 0.0);
- #endif
-+#endif
- 
- }
- #endif
- 
- #ifdef WR_FRAGMENT_SHADER
-@@ -205,11 +235,13 @@
-     vec3 plane_tr = vec3(vClipPlane_A.w, vClipPlane_B.x, vClipPlane_B.y);
-     vec3 plane_br = vec3(vClipPlane_B.z, vClipPlane_B.w, vClipPlane_C.x);
-     vec3 plane_bl = vec3(vClipPlane_C.y, vClipPlane_C.z, vClipPlane_C.w);
- 
-     float dist;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     if (vClipShape == vec4(1.0)) {
-+#endif
-         dist = distance_to_rounded_rect(
-             clip_local_pos,
-             plane_tl,
-             vClipCenter_Radius_TL,
-             plane_tr,
-@@ -218,10 +250,11 @@
-             vClipCenter_Radius_BR,
-             plane_bl,
-             vClipCenter_Radius_BL,
-             vTransformBounds
-         );
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     } else {
-         dist = distance_to_shaped_rect(
-             clip_local_pos,
-             vClipCenter_Radius_TL,
-             vClipCenter_Radius_TR,
-@@ -230,10 +263,11 @@
-             vTransformBounds,
-             vClipShape,
-             vClipClampedInset
-         );
-     }
-+#endif
- #endif
- 
-     // Compute AA for the given dist and range.
-     float alpha = distance_aa(aa_range, dist);
- 
-@@ -340,13 +374,13 @@
-         #define AA_RECT(local_pos) \
-             sd_round_box(local_pos, v_clip_size, v_clip_radii)
-     #else
-         // The span fast path only handles elliptical corners. For superellipse
-         // shapes, bail out and let SWGL fall back to the fragment shader.
--        if (vClipShape != vec4(1.0)) {
-+        #ifdef WR_FEATURE_SUPERELLIPSE
-             return;
--        }
-+        #endif
- 
-         // Unpack the corner half-spaces packed into vClipPlane_A/B/C.
-         vec3 plane_tl = vec3(vClipPlane_A.x, vClipPlane_A.y, vClipPlane_A.z);
-         vec3 plane_tr = vec3(vClipPlane_A.w, vClipPlane_B.x, vClipPlane_B.y);
-         vec3 plane_br = vec3(vClipPlane_B.z, vClipPlane_B.w, vClipPlane_C.x);
-diff --git a/gfx/wr/webrender/src/batch.rs b/gfx/wr/webrender/src/batch.rs
---- a/gfx/wr/webrender/src/batch.rs
-+++ b/gfx/wr/webrender/src/batch.rs
-@@ -1224,25 +1224,29 @@
- /// A list of clip instances to be drawn into a target.
- #[cfg_attr(feature = "capture", derive(Serialize))]
- #[cfg_attr(feature = "replay", derive(Deserialize))]
- pub struct ClipMaskInstanceList {
-     pub mask_instances_fast: FrameVec<MaskInstance>,
-+    pub mask_instances_superellipse: FrameVec<MaskInstance>,
-     pub mask_instances_slow: FrameVec<MaskInstance>,
- 
-     pub mask_instances_fast_with_scissor: FastHashMap<DeviceIntRect, FrameVec<MaskInstance>>,
-+    pub mask_instances_superellipse_with_scissor: FastHashMap<DeviceIntRect, FrameVec<MaskInstance>>,
-     pub mask_instances_slow_with_scissor: FastHashMap<DeviceIntRect, FrameVec<MaskInstance>>,
- 
-     pub image_mask_instances: FastHashMap<TextureSource, FrameVec<PrimitiveInstanceData>>,
-     pub image_mask_instances_with_scissor: FastHashMap<(DeviceIntRect, TextureSource), FrameVec<PrimitiveInstanceData>>,
- }
- 
- impl ClipMaskInstanceList {
-     pub fn new(memory: &FrameMemory) -> Self {
-         ClipMaskInstanceList {
-             mask_instances_fast: memory.new_vec(),
-+            mask_instances_superellipse: memory.new_vec(),
-             mask_instances_slow: memory.new_vec(),
-             mask_instances_fast_with_scissor: FastHashMap::default(),
-+            mask_instances_superellipse_with_scissor: FastHashMap::default(),
-             mask_instances_slow_with_scissor: FastHashMap::default(),
-             image_mask_instances: FastHashMap::default(),
-             image_mask_instances_with_scissor: FastHashMap::default(),
-         }
-     }
-@@ -1250,20 +1254,24 @@
-     pub fn is_empty(&self) -> bool {
-         // Destructure self to make sure we don't forget to update this method if
-         // a new member is added.
-         let ClipMaskInstanceList {
-             mask_instances_fast,
-+            mask_instances_superellipse,
-             mask_instances_slow,
-             mask_instances_fast_with_scissor,
-+            mask_instances_superellipse_with_scissor,
-             mask_instances_slow_with_scissor,
-             image_mask_instances,
-             image_mask_instances_with_scissor,
-         } = self;
- 
-         mask_instances_fast.is_empty()
-+            && mask_instances_superellipse.is_empty()
-             && mask_instances_slow.is_empty()
-             && mask_instances_fast_with_scissor.is_empty()
-+            && mask_instances_superellipse_with_scissor.is_empty()
-             && mask_instances_slow_with_scissor.is_empty()
-             && image_mask_instances.is_empty()
-             && image_mask_instances_with_scissor.is_empty()
-     }
- }
-diff --git a/gfx/wr/webrender/src/quad.rs b/gfx/wr/webrender/src/quad.rs
---- a/gfx/wr/webrender/src/quad.rs
-+++ b/gfx/wr/webrender/src/quad.rs
-@@ -1807,11 +1807,11 @@
-     gpu_buffer: &mut GpuBufferBuilderF,
-     clip_rect: LayoutRect,
-     radius: &BorderRadius,
-     inset: LayoutSideOffsets,
-     mode: ClipMode,
--) -> (GpuBufferAddress, bool) {
-+) -> (GpuBufferAddress, bool, bool) {
-     let radius = clamped_radius(radius, clip_rect.size());
- 
-     if radius.can_use_fast_path_in(&clip_rect) {
-         let mut writer = gpu_buffer.write_blocks(3);
-         writer.push_one(clip_rect);
-@@ -1821,13 +1821,15 @@
-             radius.bottom_left.width,
-             radius.top_left.width,
-         ]);
-         writer.push_one([mode as i32 as f32, 0.0, 0.0, 0.0]);
- 
--        (writer.finish(), true)
-+        (writer.finish(), true, false)
-     } else {
--        let mut writer = gpu_buffer.write_blocks(6);
-+        let superellipse = !radius.shapes_all_round();
-+        let block_count = if superellipse { 6 } else { 4 };
-+        let mut writer = gpu_buffer.write_blocks(block_count);
-         writer.push_one(clip_rect);
-         writer.push_one([
-             radius.top_left.width,
-             radius.top_left.height,
-             radius.top_right.width,
-@@ -1838,19 +1840,21 @@
-             radius.bottom_left.height,
-             radius.bottom_right.width,
-             radius.bottom_right.height,
-         ]);
-         writer.push_one([mode as i32 as f32, 0.0, 0.0, 0.0]);
--        writer.push_one([
--            radius.shape_top_left,
--            radius.shape_top_right,
--            radius.shape_bottom_right,
--            radius.shape_bottom_left,
--        ]);
--        writer.push_one(inset);
-+        if superellipse {
-+            writer.push_one([
-+                radius.shape_top_left,
-+                radius.shape_top_right,
-+                radius.shape_bottom_right,
-+                radius.shape_bottom_left,
-+            ]);
-+            writer.push_one(inset);
-+        }
- 
--        (writer.finish(), false)
-+        (writer.finish(), false, superellipse)
-     }
- }
- 
- pub fn prepare_clip_task(
-     clip_instance: &ClipNodeInstance,
-@@ -1865,11 +1869,11 @@
-     gpu_buffer: &mut GpuBufferBuilderF,
-     transforms: &mut TransformPalette,
-     rg_builder: &mut RenderTaskGraphBuilder,
-     sub_tasks: &mut SubTaskRange,
- ) {
--    let (clip_address, fast_path) = match clip_item.kind {
-+    let (clip_address, fast_path, superellipse) = match clip_item.kind {
-         ClipItemKind::RoundedRectangle { radius, inset, mode } => {
-             write_rounded_rect_clip_blocks(
-                 gpu_buffer,
-                 clip_instance.clip_rect,
-                 &radius,
-@@ -1882,11 +1886,11 @@
-             writer.push_one(clip_instance.clip_rect);
-             writer.push_one([0.0, 0.0, 0.0, 0.0]);
-             writer.push_one([mode as i32 as f32, 0.0, 0.0, 0.0]);
-             let clip_address = writer.finish();
- 
--            (clip_address, true)
-+            (clip_address, true, false)
-         }
-         ClipItemKind::Image { .. } => {
-             let transform_id = transforms.gpu.get_id_with_post_scale(
-                 clip_instance.spatial_node_index,
-                 raster_spatial_node_index,
-@@ -2033,10 +2037,11 @@
-             clip_transform_id,
-             quad_flags,
-             clip_space,
-             needs_scissor_rect,
-             rounded_rect_fast_path: fast_path,
-+            rounded_rect_superellipse: superellipse,
-         }),
-     );
- }
- 
- fn create_quad_primitive(
-diff --git a/gfx/wr/webrender/src/render_target.rs b/gfx/wr/webrender/src/render_target.rs
---- a/gfx/wr/webrender/src/render_target.rs
-+++ b/gfx/wr/webrender/src/render_target.rs
-@@ -441,11 +441,11 @@
-                 // so the target must be initialized to one.
-                 self.clears.push((target_rect, ColorF::WHITE));
- 
-                 let device_rect = DeviceRect::from_size(target_rect.size().to_f32());
- 
--                let (clip_address, fast_path) = quad::write_rounded_rect_clip_blocks(
-+                let (clip_address, fast_path, superellipse) = quad::write_rounded_rect_clip_blocks(
-                     &mut gpu_buffer_builder.f32,
-                     region_task.clip_rect,
-                     &region_task.radius,
-                     region_task.inset,
-                     region_task.mode,
-@@ -495,10 +495,12 @@
-                             unused: 0,
-                         };
- 
-                         if fast_path {
-                             self.clip_masks.mask_instances_fast.push(instance);
-+                        } else if superellipse {
-+                            self.clip_masks.mask_instances_superellipse.push(instance);
-                         } else {
-                             self.clip_masks.mask_instances_slow.push(instance);
-                         }
-                     },
-                 );
-@@ -925,19 +927,26 @@
-                 if task.rounded_rect_fast_path {
-                     results.mask_instances_fast_with_scissor
-                             .entry(*target_rect)
-                             .or_insert_with(|| memory.new_vec())
-                             .push(instance);
-+                } else if task.rounded_rect_superellipse {
-+                    results.mask_instances_superellipse_with_scissor
-+                            .entry(*target_rect)
-+                            .or_insert_with(|| memory.new_vec())
-+                            .push(instance);
-                 } else {
-                     results.mask_instances_slow_with_scissor
-                             .entry(*target_rect)
-                             .or_insert_with(|| memory.new_vec())
-                             .push(instance);
-                 }
-             } else {
-                 if task.rounded_rect_fast_path {
-                     results.mask_instances_fast.push(instance);
-+                } else if task.rounded_rect_superellipse {
-+                    results.mask_instances_superellipse.push(instance);
-                 } else {
-                     results.mask_instances_slow.push(instance);
-                 }
-             }
-         }
-diff --git a/gfx/wr/webrender/src/render_task.rs b/gfx/wr/webrender/src/render_task.rs
---- a/gfx/wr/webrender/src/render_task.rs
-+++ b/gfx/wr/webrender/src/render_task.rs
-@@ -2240,10 +2240,11 @@
-     /// Transform from the quad primitive's space to the clip's local space.
-     pub clip_transform_id: GpuTransformId,
-     pub quad_flags: QuadFlags,
-     pub needs_scissor_rect: bool,
-     pub rounded_rect_fast_path: bool,
-+    pub rounded_rect_superellipse: bool,
- }
- 
- /// An clip applied to a render task using the multiply blend mode on top of
- /// the content being clipped.
- #[derive(Debug)]
-diff --git a/gfx/wr/webrender/src/renderer/mod.rs b/gfx/wr/webrender/src/renderer/mod.rs
---- a/gfx/wr/webrender/src/renderer/mod.rs
-+++ b/gfx/wr/webrender/src/renderer/mod.rs
-@@ -2450,10 +2450,54 @@
-                 }
- 
-                 self.device.disable_scissor();
-             }
- 
-+            if !masks.mask_instances_superellipse.is_empty() {
-+                self.shaders.borrow_mut().ps_mask_superellipse().bind(
-+                    &mut self.device,
-+                    projection,
-+                    None,
-+                    &mut self.renderer_errors,
-+                    &mut self.profile,
-+                    &mut self.command_log,
-+                );
-+
-+                self.draw_instanced_batch(
-+                    &masks.mask_instances_superellipse,
-+                    VertexArrayKind::Mask,
-+                    &BatchTextures::empty(),
-+                    stats,
-+                );
-+            }
-+
-+            if !masks.mask_instances_superellipse_with_scissor.is_empty() {
-+                self.shaders.borrow_mut().ps_mask_superellipse().bind(
-+                    &mut self.device,
-+                    projection,
-+                    None,
-+                    &mut self.renderer_errors,
-+                    &mut self.profile,
-+                    &mut self.command_log,
-+                );
-+
-+                self.device.enable_scissor();
-+
-+                for (scissor_rect, instances) in &masks.mask_instances_superellipse_with_scissor {
-+                    self.device.set_scissor_rect(draw_target.to_framebuffer_rect(*scissor_rect));
-+
-+                    self.draw_instanced_batch(
-+                        instances,
-+                        VertexArrayKind::Mask,
-+                        &BatchTextures::empty(),
-+                        stats,
-+                    );
-+                }
-+
-+                self.device.disable_scissor();
-+            }
-+
-             if !masks.image_mask_instances.is_empty() {
-                 self.shaders.borrow_mut().ps_quad_textured().bind(
-                     &mut self.device,
-                     projection,
-                     None,
-diff --git a/gfx/wr/webrender/src/renderer/shade.rs b/gfx/wr/webrender/src/renderer/shade.rs
---- a/gfx/wr/webrender/src/renderer/shade.rs
-+++ b/gfx/wr/webrender/src/renderer/shade.rs
-@@ -65,10 +65,11 @@
- ];
- 
- const DITHERING_FEATURE: &str = "DITHERING";
- const DUAL_SOURCE_FEATURE: &str = "DUAL_SOURCE_BLENDING";
- const FAST_PATH_FEATURE: &str = "FAST_PATH";
-+const SUPERELLIPSE_FEATURE: &str = "SUPERELLIPSE";
- 
- pub(crate) enum ShaderKind {
-     Primitive,
-     Cache(VertexArrayKind),
-     Text,
-@@ -449,10 +450,11 @@
-     ps_quad_backdrop: ShaderHandle,
-     ps_quad_blend: ShaderHandle,
-     ps_quad_mix_blend: ShaderHandle,
-     ps_mask: ShaderHandle,
-     ps_mask_fast: ShaderHandle,
-+    ps_mask_superellipse: ShaderHandle,
-     ps_clear: ShaderHandle,
-     ps_copy: ShaderHandle,
- 
-     composite: CompositorShaders,
- }
-@@ -514,10 +516,17 @@
-             "ps_quad_mask",
-             &[FAST_PATH_FEATURE],
-             &shader_list,
-         )?;
- 
-+        let ps_mask_superellipse = loader.create_shader(
-+            ShaderKind::Cache(VertexArrayKind::Mask),
-+            "ps_quad_mask",
-+            &[SUPERELLIPSE_FEATURE],
-+            &shader_list,
-+        )?;
-+
-         let mut cs_scale = Vec::new();
-         let scale_shader_num = IMAGE_BUFFER_KINDS.len();
-         // PrimitiveShader is not clonable. Use push() to initialize the vec.
-         for _ in 0 .. scale_shader_num {
-             cs_scale.push(None);
-@@ -786,10 +795,11 @@
-             ps_quad_backdrop,
-             ps_quad_blend,
-             ps_quad_mix_blend,
-             ps_mask,
-             ps_mask_fast,
-+            ps_mask_superellipse,
-             ps_split_composite,
-             ps_clear,
-             ps_copy,
-             composite,
-         })
-@@ -963,10 +973,11 @@
-     pub fn ps_quad_textured(&mut self) -> &mut LazilyCompiledShader {
-         self.loader.get(self.ps_quad_textured)
-     }
-     pub fn ps_mask(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.ps_mask) }
-     pub fn ps_mask_fast(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.ps_mask_fast) }
-+    pub fn ps_mask_superellipse(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.ps_mask_superellipse) }
-     pub fn ps_clear(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.ps_clear) }
-     pub fn ps_copy(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.ps_copy) }
- 
-     pub fn deinit(self, device: &mut Device) {
-         self.loader.deinit(device);
-diff --git a/gfx/wr/webrender_build/src/shader_features.rs b/gfx/wr/webrender_build/src/shader_features.rs
---- a/gfx/wr/webrender_build/src/shader_features.rs
-+++ b/gfx/wr/webrender_build/src/shader_features.rs
-@@ -65,11 +65,11 @@
-     let mut shaders = ShaderFeatures::new();
- 
-     // Cache shaders
-     shaders.insert("cs_blur", vec!["ALPHA_TARGET".to_string(), "COLOR_TARGET".to_string()]);
- 
--    shaders.insert("ps_quad_mask", vec![String::new(), "FAST_PATH".to_string()]);
-+    shaders.insert("ps_quad_mask", vec![String::new(), "FAST_PATH".to_string(), "SUPERELLIPSE".to_string()]);
- 
-     for name in &[
-         "cs_line_decoration",
-         "cs_border_segment",
-         "cs_border_solid",
-
diff --git a/src/external-patches/firefox/bug_2063169/D319796.patch b/src/external-patches/firefox/bug_2063169/D319796.patch
deleted file mode 100644
index 57fe3d00b..000000000
--- a/src/external-patches/firefox/bug_2063169/D319796.patch
+++ /dev/null
@@ -1,307 +0,0 @@
-diff --git a/gfx/wr/webrender/res/ps_quad_box_shadow.glsl b/gfx/wr/webrender/res/ps_quad_box_shadow.glsl
---- a/gfx/wr/webrender/res/ps_quad_box_shadow.glsl
-+++ b/gfx/wr/webrender/res/ps_quad_box_shadow.glsl
-@@ -49,22 +49,26 @@
- flat varying highp vec4 vElemCenter_Radius_TL;
- flat varying highp vec4 vElemCenter_Radius_TR;
- flat varying highp vec4 vElemCenter_Radius_BR;
- flat varying highp vec4 vElemCenter_Radius_BL;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
- flat varying highp vec4 vElemShape;
-+#endif
- 
- #ifdef WR_VERTEX_SHADER
- 
- void pattern_vertex(PrimitiveInfo info) {
-     vec4 data0 = fetch_from_gpu_buffer_1f(info.pattern_input.x);
-     vec4 data1 = fetch_from_gpu_buffer_1f(info.pattern_input.x + 1);
-     vec4 data2 = fetch_from_gpu_buffer_1f(info.pattern_input.x + 2);
-     vec4 data3 = fetch_from_gpu_buffer_1f(info.pattern_input.x + 3);
-     vec4 data4 = fetch_from_gpu_buffer_1f(info.pattern_input.x + 4);
-     vec4 data5 = fetch_from_gpu_buffer_1f(info.pattern_input.x + 5);
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vec4 data6 = fetch_from_gpu_buffer_1f(info.pattern_input.x + 6);
-+#endif
- 
-     vec2 alloc_size     = data0.xy;
-     vec2 dest_rect_size = data0.zw;
-     vec2 dest_rect_off  = data1.xy;
-     v_uv_scale_inset    = vec4(vec2(1.0) / alloc_size, data1.z, 0.0);
-@@ -84,11 +88,11 @@
-     // Map nine-patch UV=1.0 to the true content edge (uv_p0 + content_device_size)
-     // rather than the rounded atlas entry edge (info.segment.uv_rect.p1). The atlas
-     // allocation is rounded up from content_device_size, so this edge always lies
-     // inside the entry; using it keeps the mapping stable to sub-texel precision as
-     // the blur animates (bug 2002194).
--    vec2 content_device_size = data6.xy;
-+    vec2 content_device_size = data5.xy;
-     vec2 texture_size = vec2(TEX_SIZE(sColor0));
-     vec2 uv_p0 = info.segment.uv_rect.p0;
-     vec2 uv_p1 = uv_p0 + content_device_size;
-     v_uv_rect = vec4(uv_p0, uv_p1) / texture_size.xyxy;
-     v_uv_bounds = vec4(
-@@ -110,11 +114,13 @@
-     vElemCenter_Radius_TL = vec4(elem_p0 + r_tl, r_tl);
-     vElemCenter_Radius_TR = vec4(elem_p1.x - r_tr.x, elem_p0.y + r_tr.y, r_tr);
-     vElemCenter_Radius_BR = vec4(elem_p1 - r_br, r_br);
-     vElemCenter_Radius_BL = vec4(elem_p0.x + r_bl.x, elem_p1.y - r_bl.y, r_bl);
- 
--    vElemShape = data5;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-+    vElemShape = data6;
-+#endif
- }
- 
- #endif
- 
- #ifdef WR_FRAGMENT_SHADER
-@@ -170,22 +176,24 @@
-     vec3 elem_plane_bl = vec3(n_bl, dot(n_bl, vec2(c_bl.x,          c_bl.y + r_bl.y)));
- 
-     // Reconstruct the element rect bounds from the TL and BR corner data.
-     vec4 elem_bounds = vec4(c_tl - r_tl, c_br + r_br);
- 
--    vec4 elem_shape = vElemShape;
--
-     float elem_dist;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-+    vec4 elem_shape = vElemShape;
-     if (elem_shape == vec4(1.0)) {
-+#endif
-         elem_dist = distance_to_rounded_rect(
-             local_pos,
-             elem_plane_tl, vec4(c_tl, inverse_radii_squared(r_tl)),
-             elem_plane_tr, vec4(c_tr, inverse_radii_squared(r_tr)),
-             elem_plane_br, vec4(c_br, inverse_radii_squared(r_br)),
-             elem_plane_bl, vec4(c_bl, inverse_radii_squared(r_bl)),
-             elem_bounds
-         );
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     } else {
-         elem_dist = distance_to_shaped_rect(
-             local_pos,
-             vec4(c_tl, elem_shape.x == 1.0 ? inverse_radii_squared(r_tl) : inverse_radii(r_tl)),
-             vec4(c_tr, elem_shape.y == 1.0 ? inverse_radii_squared(r_tr) : inverse_radii(r_tr)),
-@@ -194,10 +202,11 @@
-             elem_bounds,
-             elem_shape,
-             vec4(0.0)
-         );
-     }
-+#endif
- 
-     // Outset (inset=0): dist < 0 = inside element → should be clipped out → use -elem_dist.
-     // Inset (inset=1): dist < 0 = inside element → should be kept → use elem_dist.
-     float element_clip = distance_aa(aa_range, mix(-elem_dist, elem_dist, inset));
- 
-diff --git a/gfx/wr/webrender/src/pattern/box_shadow.rs b/gfx/wr/webrender/src/pattern/box_shadow.rs
---- a/gfx/wr/webrender/src/pattern/box_shadow.rs
-+++ b/gfx/wr/webrender/src/pattern/box_shadow.rs
-@@ -41,11 +41,14 @@
-         _sub_rect: Option<DeviceRect>,
-         _offset: LayoutVector2D,
-         _ctx: &PatternBuilderContext,
-         state: &mut PatternBuilderState,
-     ) -> Pattern {
--        let mut writer = state.frame_gpu_data.f32.write_blocks(7);
-+        let superellipse = !self.element_radius.shapes_all_round();
-+
-+        let block_count = if superellipse { 7 } else { 6 };
-+        let mut writer = state.frame_gpu_data.f32.write_blocks(block_count);
-         writer.push_one([
-             self.shadow_rect_alloc_size.width,
-             self.shadow_rect_alloc_size.height,
-             self.dest_rect_size.width,
-             self.dest_rect_size.height,
-@@ -72,26 +75,28 @@
-             self.element_radius.bottom_right.width,
-             self.element_radius.bottom_right.height,
-             self.element_radius.bottom_left.width,
-             self.element_radius.bottom_left.height,
-         ]);
--        writer.push_one([
--            self.element_radius.shape_top_left,
--            self.element_radius.shape_top_right,
--            self.element_radius.shape_bottom_right,
--            self.element_radius.shape_bottom_left,
--        ]);
-         writer.push_one([
-             self.content_device_size.width,
-             self.content_device_size.height,
-             0.0,
-             0.0,
-         ]);
-+        if superellipse {
-+            writer.push_one([
-+                self.element_radius.shape_top_left,
-+                self.element_radius.shape_top_right,
-+                self.element_radius.shape_bottom_right,
-+                self.element_radius.shape_bottom_left,
-+            ]);
-+        }
-         let addr = writer.finish();
- 
-         Pattern {
--            kind: PatternKind::BoxShadow,
-+            kind: if superellipse { PatternKind::BoxShadowSuperellipse } else { PatternKind::BoxShadow },
-             shader_input: PatternShaderInput(addr.as_int(), 0),
-             texture_input: PatternTextureInput::new(self.render_task),
-             base_color: self.color,
-             is_opaque: false,
-             blend_mode: BlendMode::PremultipliedAlpha,
-diff --git a/gfx/wr/webrender/src/pattern/mod.rs b/gfx/wr/webrender/src/pattern/mod.rs
---- a/gfx/wr/webrender/src/pattern/mod.rs
-+++ b/gfx/wr/webrender/src/pattern/mod.rs
-@@ -29,36 +29,37 @@
-     Gradient = 1,
-     Repeat = 2,
- 
-     Mask = 3,
-     BoxShadow = 4,
-+    BoxShadowSuperellipse = 5,
-     // Variants of ColorOrTexture that use a non-default sampler type
-     // (samplerExternalOES / __samplerExternal2DY2YEXT / sampler2DRect). The
-     // quad shader is compiled in matching per-kind variants; see
-     // ps_quad_textured.glsl.
--    TextureExternal = 5,
--    TextureExternalBT709 = 6,
--    TextureRect = 7,
-+    TextureExternal = 6,
-+    TextureExternalBT709 = 7,
-+    TextureRect = 8,
-     // Samples up to three planes (sColor0/1/2) and converts from YUV to RGB.
-     // Like ColorOrTexture, the YUV pattern comes in sampler-type-specific
-     // variants so that the planes are sampled with the matching sColor
-     // declaration; see ps_quad_yuv.glsl. `Yuv` is the default (TEXTURE_2D).
--    Yuv = 8,
--    YuvTextureExternal = 9,
--    YuvTextureExternalBT709 = 10,
--    YuvTextureRect = 11,
-+    Yuv = 9,
-+    YuvTextureExternal = 10,
-+    YuvTextureExternalBT709 = 11,
-+    YuvTextureRect = 12,
-     // Samples a captured backdrop texture using a (bilerp) 4-corner uv quad.
--    Backdrop = 12,
-+    Backdrop = 13,
-     // Applies a filter to a sampled source texture; see ps_quad_blend.glsl.
--    Blend = 13,
-+    Blend = 14,
-     // Composites a picture over its backdrop with a software mix-blend-mode;
-     // samples two textures (backdrop + source). See ps_quad_mix_blend.glsl.
--    MixBlend = 14,
-+    MixBlend = 15,
-     // When adding patterns, don't forget to update the NUM_PATTERNS constant.
- }
- 
--pub const NUM_PATTERNS: u32 = 15;
-+pub const NUM_PATTERNS: u32 = 16;
- 
- impl PatternKind {
-     pub fn from_u32(val: u32) -> Self {
-         assert!(val < NUM_PATTERNS);
-         unsafe { std::mem::transmute(val) }
-diff --git a/gfx/wr/webrender/src/renderer/mod.rs b/gfx/wr/webrender/src/renderer/mod.rs
---- a/gfx/wr/webrender/src/renderer/mod.rs
-+++ b/gfx/wr/webrender/src/renderer/mod.rs
-@@ -251,10 +251,11 @@
-             BatchKind::Quad(PatternKind::TextureExternalBT709) => GPU_TAG_PRIMITIVE,
-             BatchKind::Quad(PatternKind::TextureRect) => GPU_TAG_PRIMITIVE,
-             BatchKind::Quad(PatternKind::Gradient) => GPU_TAG_GRADIENT,
-             BatchKind::Quad(PatternKind::Repeat) => GPU_TAG_REPEAT,
-             BatchKind::Quad(PatternKind::BoxShadow) => GPU_TAG_PRIMITIVE,
-+            BatchKind::Quad(PatternKind::BoxShadowSuperellipse) => GPU_TAG_PRIMITIVE,
-             BatchKind::Quad(PatternKind::Yuv) => GPU_TAG_BRUSH_YUV_IMAGE,
-             BatchKind::Quad(PatternKind::YuvTextureExternal) => GPU_TAG_BRUSH_YUV_IMAGE,
-             BatchKind::Quad(PatternKind::YuvTextureExternalBT709) => GPU_TAG_BRUSH_YUV_IMAGE,
-             BatchKind::Quad(PatternKind::YuvTextureRect) => GPU_TAG_BRUSH_YUV_IMAGE,
-             BatchKind::Quad(PatternKind::Backdrop) => GPU_TAG_PRIMITIVE,
-diff --git a/gfx/wr/webrender/src/renderer/shade.rs b/gfx/wr/webrender/src/renderer/shade.rs
---- a/gfx/wr/webrender/src/renderer/shade.rs
-+++ b/gfx/wr/webrender/src/renderer/shade.rs
-@@ -438,10 +438,11 @@
-     ps_quad_textured_external_bt709: Option<ShaderHandle>,
-     ps_quad_textured_rect: Option<ShaderHandle>,
-     ps_quad_repeat: ShaderHandle,
-     ps_quad_gradient: ShaderHandle,
-     ps_quad_box_shadow: ShaderHandle,
-+    ps_quad_box_shadow_superellipse: ShaderHandle,
-     // ps_quad_yuv, like ps_quad_textured, comes in sampler-type-specific
-     // variants so the YUV planes are sampled with the matching sColor
-     // declaration. The variant is selected via PatternKind.
-     ps_quad_yuv: ShaderHandle,
-     ps_quad_yuv_external: Option<ShaderHandle>,
-@@ -651,10 +652,17 @@
-             "ps_quad_box_shadow",
-             &[],
-             &shader_list,
-         )?;
- 
-+        let ps_quad_box_shadow_superellipse = loader.create_shader(
-+            ShaderKind::Primitive,
-+            "ps_quad_box_shadow",
-+            &[SUPERELLIPSE_FEATURE],
-+            &shader_list,
-+        )?;
-+
-         let ps_quad_yuv = loader.create_shader(
-             ShaderKind::Primitive,
-             "ps_quad_yuv",
-             &["TEXTURE_2D"],
-             &shader_list,
-@@ -786,10 +794,11 @@
-             ps_quad_textured_external_bt709,
-             ps_quad_textured_rect,
-             ps_quad_repeat,
-             ps_quad_gradient,
-             ps_quad_box_shadow,
-+            ps_quad_box_shadow_superellipse,
-             ps_quad_yuv,
-             ps_quad_yuv_external,
-             ps_quad_yuv_external_bt709,
-             ps_quad_yuv_rect,
-             ps_quad_backdrop,
-@@ -867,10 +876,11 @@
-             PatternKind::TextureRect => self.ps_quad_textured_rect
-                 .expect("bug: ps_quad_textured TEXTURE_RECT variant not loaded"),
-             PatternKind::Gradient => self.ps_quad_gradient,
-             PatternKind::Repeat => self.ps_quad_repeat,
-             PatternKind::BoxShadow => self.ps_quad_box_shadow,
-+            PatternKind::BoxShadowSuperellipse => self.ps_quad_box_shadow_superellipse,
-             PatternKind::Yuv => self.ps_quad_yuv,
-             PatternKind::YuvTextureExternal => self.ps_quad_yuv_external
-                 .expect("bug: ps_quad_yuv TEXTURE_EXTERNAL variant not loaded"),
-             PatternKind::YuvTextureExternalBT709 => self.ps_quad_yuv_external_bt709
-                 .expect("bug: ps_quad_yuv TEXTURE_EXTERNAL_BT709 variant not loaded"),
-@@ -923,10 +933,13 @@
-                 self.ps_quad_repeat
-             }
-             BatchKind::Quad(PatternKind::BoxShadow) => {
-                 self.ps_quad_box_shadow
-             }
-+            BatchKind::Quad(PatternKind::BoxShadowSuperellipse) => {
-+                self.ps_quad_box_shadow_superellipse
-+            }
-             BatchKind::Quad(PatternKind::Yuv) => {
-                 self.ps_quad_yuv
-             }
-             BatchKind::Quad(PatternKind::YuvTextureExternal) => {
-                 self.ps_quad_yuv_external
-diff --git a/gfx/wr/webrender_build/src/shader_features.rs b/gfx/wr/webrender_build/src/shader_features.rs
---- a/gfx/wr/webrender_build/src/shader_features.rs
-+++ b/gfx/wr/webrender_build/src/shader_features.rs
-@@ -166,11 +166,11 @@
-     }
-     shaders.insert("ps_quad_textured", ps_quad_textured_features);
- 
-     shaders.insert("ps_quad_repeat", vec![base_prim_features.finish()]);
- 
--    shaders.insert("ps_quad_box_shadow", vec![base_prim_features.finish()]);
-+    shaders.insert("ps_quad_box_shadow", vec![base_prim_features.finish(), "SUPERELLIPSE".to_string()]);
- 
-     // Like ps_quad_textured, ps_quad_yuv needs per-texture-kind variants so that
-     // the YUV planes are sampled with the correct sampler type.
-     let mut ps_quad_yuv_features: Vec<String> = vec!["TEXTURE_2D".to_string()];
-     if flags.contains(ShaderFeatureFlags::GL) {
-
diff --git a/src/external-patches/firefox/bug_2063169/D319869.patch b/src/external-patches/firefox/bug_2063169/D319869.patch
deleted file mode 100644
index 21d34687e..000000000
--- a/src/external-patches/firefox/bug_2063169/D319869.patch
+++ /dev/null
@@ -1,560 +0,0 @@
-diff --git a/gfx/wr/webrender/res/border_shared.glsl b/gfx/wr/webrender/res/border_shared.glsl
---- a/gfx/wr/webrender/res/border_shared.glsl
-+++ b/gfx/wr/webrender/res/border_shared.glsl
-@@ -27,25 +27,33 @@
-     vec4 rect;
-     vec4 color0;
-     vec4 color1;
-     vec2 widths;
-     vec2 radii;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     float shape;
-     vec2 shape_offset;
-     vec2 inset;
-+#endif
- };
- 
- BorderInstanceGpuData fetch_gpu_data(int index) {
-     BorderInstanceGpuData data;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vec4 texels[6] = fetch_from_gpu_buffer_6f(index);
-+#else
-+    vec4 texels[4] = fetch_from_gpu_buffer_4f(index);
-+#endif
-     data.rect = texels[0];
-     data.color0 = texels[1];
-     data.color1 = texels[2];
-     data.widths = texels[3].xy;
-     data.radii = texels[3].zw;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     data.shape = texels[4].x;
-     data.shape_offset = texels[4].yz;
-     data.inset = texels[5].xy;
-+#endif
- 
-     return data;
- }
-diff --git a/gfx/wr/webrender/res/cs_border_segment.glsl b/gfx/wr/webrender/res/cs_border_segment.glsl
---- a/gfx/wr/webrender/res/cs_border_segment.glsl
-+++ b/gfx/wr/webrender/res/cs_border_segment.glsl
-@@ -30,11 +30,13 @@
- flat varying highp vec4 vClipCenter_Sign;
- 
- // An outer and inner elliptical radii for border
- // corner clipping.
- flat varying highp vec4 vClipRadii;
-+#ifdef WR_FEATURE_SUPERELLIPSE
- flat varying highp vec4 vClipOffsets;
-+#endif
- 
- // Reference point for determine edge clip lines.
- flat varying highp vec4 vEdgeReference;
- 
- // Stores widths/2 and widths/3 to save doing this in FS.
-@@ -192,26 +194,34 @@
-     vColor00 = color0[0];
-     vColor01 = color0[1];
-     vec4[2] color1 = get_colors_for_side(data.color1, style1);
-     vColor10 = color1[0];
-     vColor11 = color1[1];
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vClipCenter_Sign = vec4(outer + clip_sign * (data.radii + data.shape_offset), clip_sign);
-+#else
-+    vClipCenter_Sign = vec4(outer + clip_sign * data.radii, clip_sign);
-+#endif
-     vClipRadii = vec4(data.radii, max(data.radii - data.widths, 0.0));
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vClipOffsets = vec4(0.0);
-+#endif
-     vColorLine = vec4(outer, data.widths.y * -clip_sign.y, data.widths.x * clip_sign.x);
-     vEdgeReference = vec4(edge_reference, edge_reference + data.widths);
-     vClipParams1 = aClipParams1;
-     vClipParams2 = aClipParams2;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     if (data.shape != 1.0)
-     {
-         vec2 reference_radii = (data.radii == vec2(0.0)) ? vec2(0.0) : data.radii + data.inset;
-         vec4 contour1 = compute_contoured_superellipse(reference_radii, data.shape, data.inset);
-         vec4 contour2 = compute_contoured_superellipse(reference_radii, data.shape, data.inset + data.widths);
-         vClipOffsets = vec4(contour1.xy, contour2.xy);
-         vClipRadii = vec4(contour1.zw, contour2.zw);
-     }
-+#endif
- 
-     // For the case of dot and dash clips, optimize the number of pixels that
-     // are hit to just include the dot itself.
-     if (clip_mode == CLIP_DOT) {
-         float radius = aClipParams1.z;
-@@ -258,19 +268,22 @@
-             // also 0.67 of the radii. Use these to form a
-             // SDF subtraction which will clip out the inside
-             // third of the rounded edge.
-             float d_radii_a;
-             float d_radii_b;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-             if (data.shape == 1.0) {
-+#endif
-                 d_radii_a = distance_to_ellipse(
-                     clip_relative_pos,
-                     clip_radii.xy - vPartialWidths.xy
-                 );
-                 d_radii_b = distance_to_ellipse(
-                     clip_relative_pos,
-                     clip_radii.xy - 2.0 * vPartialWidths.xy
-                 );
-+#ifdef WR_FEATURE_SUPERELLIPSE
-             } else {
-                 d_radii_a = distance_to_superellipse(
-                     clip_relative_pos - mix(vClipOffsets.xy, vClipOffsets.zw, 1.0 / 3.0),
-                     mix(clip_radii.xy, clip_radii.zw, 1.0 / 3.0),
-                     data.shape
-@@ -286,24 +299,28 @@
-                 d_radii_a = max(d_radii_a, -min(included_region_a.x, included_region_a.y));
- 
-                 vec2 included_region_b = data.radii - 2.0 * vPartialWidths.xy - clip_relative_pos;
-                 d_radii_b = max(d_radii_b, -min(included_region_b.x, included_region_b.y));
-             }
-+#endif
- 
-             float d = min(-d_radii_a, d_radii_b);
- 
-             color0 *= distance_aa(aa_range, d);
-             break;
-         }
-         case BORDER_STYLE_GROOVE:
-         case BORDER_STYLE_RIDGE: {
-             float d;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-             if (data.shape == 1.0) {
-+#endif
-                 d = distance_to_ellipse(
-                     clip_relative_pos,
-                     clip_radii.xy - vPartialWidths.zw
-                 );
-+#ifdef WR_FEATURE_SUPERELLIPSE
-             } else {
-                 d = distance_to_superellipse(
-                     clip_relative_pos - mix(vClipOffsets.xy, vClipOffsets.zw, 0.5),
-                     mix(clip_radii.xy, clip_radii.zw, 0.5),
-                     data.shape
-@@ -311,10 +328,11 @@
- 
-                 // Clamp to the middle of the adjacent borders
-                 vec2 included_region = data.radii - vPartialWidths.zw - clip_relative_pos;
-                 d = max(d, -min(included_region.x, included_region.y));
-             }
-+#endif
-             float alpha = distance_aa(aa_range, d);
-             float swizzled_factor;
-             switch (segment) {
-                 case SEGMENT_TOP_LEFT: swizzled_factor = 0.0; break;
-                 case SEGMENT_TOP_RIGHT: swizzled_factor = mix_factor; break;
-@@ -435,22 +453,26 @@
- 
-     if (in_clip_region) {
-         float d_radii_a;
-         float d_radii_b;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-         if (data.shape == 1.0) {
-+#endif
-             d_radii_a = distance_to_ellipse(clip_relative_pos, vClipRadii.xy);
-             d_radii_b = distance_to_ellipse(clip_relative_pos, vClipRadii.zw);
-+#ifdef WR_FEATURE_SUPERELLIPSE
-         } else {
-             clip_relative_pos = abs(clip_relative_pos) - data.shape_offset;
-             d_radii_a = distance_to_superellipse(clip_relative_pos - vClipOffsets.xy, vClipRadii.xy, data.shape);
-             d_radii_b = distance_to_superellipse(clip_relative_pos - vClipOffsets.zw, vClipRadii.zw, data.shape);
- 
-             // exclude the straight border part from the subtracted region
-             vec2 included_region = data.radii - data.widths - clip_relative_pos;
-             d_radii_b = max(d_radii_b, -min(included_region.x, included_region.y));
-         }
-+#endif
- 
-         float d_radii = max(d_radii_a, -d_radii_b);
-         d = max(d, d_radii);
-         
-         color0 = evaluate_color_for_style_in_corner(
-diff --git a/gfx/wr/webrender/res/cs_border_solid.glsl b/gfx/wr/webrender/res/cs_border_solid.glsl
---- a/gfx/wr/webrender/res/cs_border_solid.glsl
-+++ b/gfx/wr/webrender/res/cs_border_solid.glsl
-@@ -31,11 +31,13 @@
- flat varying highp vec4 vClipCenter_Sign;
- 
- // An outer and inner elliptical radii for border
- // corner clipping.
- flat varying highp vec4 vClipRadii;
-+#ifdef WR_FEATURE_SUPERELLIPSE
- flat varying highp vec4 vClipOffsets;
-+#endif
- 
- // Position, scale, and radii of horizontally and vertically adjacent corner clips.
- flat varying highp vec4 vHorizontalClipCenter_Sign;
- flat varying highp vec2 vHorizontalClipRadii;
- flat varying highp vec4 vVerticalClipCenter_Sign;
-@@ -74,11 +76,11 @@
- void main(void) {
-     BorderInstanceGpuData data = fetch_gpu_data(aGpuDataAddress);
-     vGpuDataAddress.x = aGpuDataAddress;
- 
-     int segment = aFlags & 0xff;
--    bool do_aa = ((aFlags >> 24) & 0xf0) != 0;
-+    bool do_aa = ((aFlags >> 28) & 0x1) != 0;
- 
-     vec2 outer_scale = get_outer_corner_scale(segment);
-     vec2 size = data.rect.zw - data.rect.xy;
-     vec2 outer = outer_scale * size;
-     vec2 clip_sign = 1.0 - 2.0 * outer_scale;
-@@ -100,23 +102,31 @@
-     vMixColors.x = mix_colors;
-     vPos = size * aPosition.xy;
- 
-     vColor0 = data.color0;
-     vColor1 = data.color1;
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vClipCenter_Sign = vec4(outer + clip_sign * (data.radii + data.shape_offset), clip_sign);
-+#else
-+    vClipCenter_Sign = vec4(outer + clip_sign * data.radii, clip_sign);
-+#endif
-     vClipRadii = vec4(data.radii, max(data.radii - data.widths, 0.0));
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     vClipOffsets = vec4(0.0);
-+#endif
-     vColorLine = vec4(outer, data.widths.y * -clip_sign.y, data.widths.x * clip_sign.x);
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-     if (data.shape != 1.0)
-     {
-         vec2 reference_radii = (data.radii == vec2(0.0)) ? vec2(0.0) : data.radii + data.inset;
-         vec4 contour1 = compute_contoured_superellipse(reference_radii, data.shape, data.inset);
-         vec4 contour2 = compute_contoured_superellipse(reference_radii, data.shape, data.inset + data.widths);
-         vClipOffsets = vec4(contour1.xy, contour2.xy);
-         vClipRadii = vec4(contour1.zw, contour2.zw);
-     }
-+#endif
- 
-     vec2 horizontal_clip_sign = vec2(-clip_sign.x, clip_sign.y);
-     vHorizontalClipCenter_Sign = vec4(aClipParams1.xy +
-                                       horizontal_clip_sign * aClipParams1.zw,
-                                       horizontal_clip_sign);
-@@ -156,22 +166,26 @@
-     float d = -1.0;
-     if (in_clip_region) {
-         float d_radii_a;
-         float d_radii_b;
- 
-+#ifdef WR_FEATURE_SUPERELLIPSE
-         if (data.shape == 1.0) {
-+#endif
-             d_radii_a = distance_to_ellipse(clip_relative_pos, vClipRadii.xy);
-             d_radii_b = distance_to_ellipse(clip_relative_pos, vClipRadii.zw);
-+#ifdef WR_FEATURE_SUPERELLIPSE
-         } else {
-             clip_relative_pos = abs(clip_relative_pos) - data.shape_offset;
-             d_radii_a = distance_to_superellipse(clip_relative_pos - vClipOffsets.xy, vClipRadii.xy, data.shape);
-             d_radii_b = distance_to_superellipse(clip_relative_pos - vClipOffsets.zw, vClipRadii.zw, data.shape);
- 
-             // exclude the straight border part from the subtracted region
-             vec2 included_region = data.radii - data.widths - clip_relative_pos;
-             d_radii_b = max(d_radii_b, -min(included_region.x, included_region.y));
-         }
-+#endif
- 
-         d = max(d_radii_a, -d_radii_b);
-     }
- 
-     // And again for horizontally-adjacent corner
-diff --git a/gfx/wr/webrender/src/border.rs b/gfx/wr/webrender/src/border.rs
---- a/gfx/wr/webrender/src/border.rs
-+++ b/gfx/wr/webrender/src/border.rs
-@@ -855,14 +855,17 @@
-     h_adjacent_corner_radius: DeviceSize,
-     v_adjacent_corner_outer: DevicePoint,
-     v_adjacent_corner_radius: DeviceSize,
-     gpu_buffer_builder: &mut GpuBufferBuilderF,
- ) {
-+    let superellipse = shape != 1.0;
-+
-     let base_flags = (segment as i32) |
-                      ((style0 as i32) << 8) |
-                      ((style1 as i32) << 16) |
--                     ((do_aa as i32) << 28);
-+                     ((do_aa as i32) << 28) |
-+                     ((superellipse as i32) << 29);
- 
-     let instance_gpu_data = BorderInstanceGpuData {
-         local_rect: task_rect,
-         color0: color0.premultiplied(),
-         color1: color1.premultiplied(),
-@@ -875,11 +878,11 @@
- 
-     let base_instance = BorderInstance {
-         task_origin: DevicePoint::zero(),
-         flags: base_flags,
-         clip_params: [0.0; 8],
--        gpu_data_address: instance_gpu_data.write(gpu_buffer_builder)
-+        gpu_data_address: instance_gpu_data.write(superellipse, gpu_buffer_builder)
-     };
- 
-     match segment {
-         BorderSegment::TopLeft |
-         BorderSegment::TopRight |
-diff --git a/gfx/wr/webrender/src/gpu_types.rs b/gfx/wr/webrender/src/gpu_types.rs
---- a/gfx/wr/webrender/src/gpu_types.rs
-+++ b/gfx/wr/webrender/src/gpu_types.rs
-@@ -192,18 +192,21 @@
-     pub shape_offset: DeviceSize,
-     pub inset: DeviceSize,
- }
- 
- impl BorderInstanceGpuData {
--    pub fn write(&self, gpu_buffer_builder: &mut GpuBufferBuilderF) -> GpuBufferAddress {
--        let mut writer = gpu_buffer_builder.write_blocks(6);
-+    pub fn write(&self, superellipse: bool, gpu_buffer_builder: &mut GpuBufferBuilderF) -> GpuBufferAddress {
-+        let block_count = if superellipse { 6 } else { 4 };
-+        let mut writer = gpu_buffer_builder.write_blocks(block_count);
-         writer.push_one(self.local_rect);
-         writer.push_one(self.color0);
-         writer.push_one(self.color1);
-         writer.push_one([self.widths.width, self.widths.height, self.radius.width, self.radius.height]);
--        writer.push_one([self.shape, self.shape_offset.width, self.shape_offset.height, 0.0]);
--        writer.push_one([self.inset.width, self.inset.height, 0.0, 0.0]);
-+        if superellipse {
-+            writer.push_one([self.shape, self.shape_offset.width, self.shape_offset.height, 0.0]);
-+            writer.push_one([self.inset.width, self.inset.height, 0.0, 0.0]);
-+        }
- 
-         writer.finish()
-     }
- }
- 
-diff --git a/gfx/wr/webrender/src/render_target.rs b/gfx/wr/webrender/src/render_target.rs
---- a/gfx/wr/webrender/src/render_target.rs
-+++ b/gfx/wr/webrender/src/render_target.rs
-@@ -33,10 +33,11 @@
- use crate::spatial_tree::SpatialNodeIndex;
- 
- 
- const STYLE_SOLID: i32 = ((BorderStyle::Solid as i32) << 8) | ((BorderStyle::Solid as i32) << 16);
- const STYLE_MASK: i32 = 0x00FF_FF00;
-+const SUPERELLIPSE_MASK: i32 = 1 << 29;
- 
- /// A tag used to identify the output format of a `RenderTarget`.
- #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
- #[cfg_attr(feature = "capture", derive(Serialize))]
- #[cfg_attr(feature = "replay", derive(Deserialize))]
-@@ -163,10 +164,12 @@
- 
-     pub clip_masks: ClipMaskInstanceList,
- 
-     pub border_segments_complex: FrameVec<BorderInstance>,
-     pub border_segments_solid: FrameVec<BorderInstance>,
-+    pub border_segments_complex_superellipse: FrameVec<BorderInstance>,
-+    pub border_segments_solid_superellipse: FrameVec<BorderInstance>,
-     pub line_decorations: FrameVec<LineDecorationJob>,
- 
-     // Clearing render targets has a fair amount of special cases.
-     // The general rules are:
-     // - Depth (for at least the used potion of the target) is always cleared if it
-@@ -223,10 +226,12 @@
-             prim_instances: std::array::from_fn(|_| FastHashMap::default()),
-             prim_instances_with_scissor: FastHashMap::default(),
-             clip_masks: ClipMaskInstanceList::new(memory),
-             border_segments_complex: memory.new_vec(),
-             border_segments_solid: memory.new_vec(),
-+            border_segments_complex_superellipse: memory.new_vec(),
-+            border_segments_solid_superellipse: memory.new_vec(),
-             clears: memory.new_vec(),
-             line_decorations: memory.new_vec(),
-         }
-     }
- 
-@@ -547,14 +552,23 @@
-                 let instances = task_info.instances.clone();
-                 for mut instance in instances {
-                     // TODO(gw): It may be better to store the task origin in
-                     //           the render task data instead of per instance.
-                     instance.task_origin = task_origin;
-+                    let superellipse = (instance.flags & SUPERELLIPSE_MASK) != 0;
-                     if instance.flags & STYLE_MASK == STYLE_SOLID {
--                        self.border_segments_solid.push(instance);
-+                        if superellipse {
-+                            self.border_segments_solid_superellipse.push(instance);
-+                        } else {
-+                            self.border_segments_solid.push(instance);
-+                        }
-                     } else {
--                        self.border_segments_complex.push(instance);
-+                        if superellipse {
-+                            self.border_segments_complex_superellipse.push(instance);
-+                        } else {
-+                            self.border_segments_complex.push(instance);
-+                        }
-                     }
-                 }
-             }
-             RenderTaskKind::Image(..) |
-             RenderTaskKind::Cached(..) |
-diff --git a/gfx/wr/webrender/src/renderer/mod.rs b/gfx/wr/webrender/src/renderer/mod.rs
---- a/gfx/wr/webrender/src/renderer/mod.rs
-+++ b/gfx/wr/webrender/src/renderer/mod.rs
-@@ -3394,11 +3394,13 @@
-             draw_target,
-         );
- 
-         // Draw any borders for this target.
-         if !target.border_segments_solid.is_empty() ||
--           !target.border_segments_complex.is_empty()
-+           !target.border_segments_complex.is_empty() ||
-+           !target.border_segments_solid_superellipse.is_empty() ||
-+           !target.border_segments_complex_superellipse.is_empty()
-         {
-             let _timer = self.gpu_profiler.start_timer(GPU_TAG_CACHE_BORDER);
- 
-             self.set_blend(true, FramebufferKind::Other);
-             self.set_blend_mode_premultiplied_alpha(FramebufferKind::Other);
-@@ -3437,10 +3439,46 @@
-                     &BatchTextures::empty(),
-                     stats,
-                 );
-             }
- 
-+            if !target.border_segments_solid_superellipse.is_empty() {
-+                self.shaders.borrow_mut().cs_border_solid_superellipse().bind(
-+                    &mut self.device,
-+                    &projection,
-+                    None,
-+                    &mut self.renderer_errors,
-+                    &mut self.profile,
-+                    &mut self.command_log,
-+                );
-+
-+                self.draw_instanced_batch(
-+                    &target.border_segments_solid_superellipse,
-+                    VertexArrayKind::Border,
-+                    &BatchTextures::empty(),
-+                    stats,
-+                );
-+            }
-+
-+            if !target.border_segments_complex_superellipse.is_empty() {
-+                self.shaders.borrow_mut().cs_border_segment_superellipse().bind(
-+                    &mut self.device,
-+                    &projection,
-+                    None,
-+                    &mut self.renderer_errors,
-+                    &mut self.profile,
-+                    &mut self.command_log,
-+                );
-+
-+                self.draw_instanced_batch(
-+                    &target.border_segments_complex_superellipse,
-+                    VertexArrayKind::Border,
-+                    &BatchTextures::empty(),
-+                    stats,
-+                );
-+            }
-+
-             self.set_blend(false, FramebufferKind::Other);
-         }
- 
-         // Draw any line decorations for this target.
-         if !target.line_decorations.is_empty() {
-diff --git a/gfx/wr/webrender/src/renderer/shade.rs b/gfx/wr/webrender/src/renderer/shade.rs
---- a/gfx/wr/webrender/src/renderer/shade.rs
-+++ b/gfx/wr/webrender/src/renderer/shade.rs
-@@ -413,10 +413,12 @@
-     // draw intermediate results to cache targets. The results
-     // of these shaders are then used by the primitive shaders.
-     cs_blur_rgba8: ShaderHandle,
-     cs_border_segment: ShaderHandle,
-     cs_border_solid: ShaderHandle,
-+    cs_border_segment_superellipse: ShaderHandle,
-+    cs_border_solid_superellipse: ShaderHandle,
-     cs_scale: Vec<Option<ShaderHandle>>,
-     cs_line_decoration: ShaderHandle,
-     cs_svg_filter_node: ShaderHandle,
- 
-     // The are "primitive shaders". These shaders draw and blend
-@@ -774,19 +776,35 @@
-             "cs_border_solid",
-             &[],
-             &shader_list,
-         )?;
- 
-+        let cs_border_segment_superellipse = loader.create_shader(
-+            ShaderKind::Cache(VertexArrayKind::Border),
-+            "cs_border_segment",
-+             &[SUPERELLIPSE_FEATURE],
-+            &shader_list,
-+        )?;
-+
-+        let cs_border_solid_superellipse = loader.create_shader(
-+            ShaderKind::Cache(VertexArrayKind::Border),
-+            "cs_border_solid",
-+            &[SUPERELLIPSE_FEATURE],
-+            &shader_list,
-+        )?;
-+
-         let composite = CompositorShaders::new(device, gl_type, &mut loader)?;
- 
-         Ok(Shaders {
-             loader,
- 
-             cs_blur_rgba8,
-             cs_border_segment,
--            cs_line_decoration,
-             cs_border_solid,
-+            cs_border_segment_superellipse,
-+            cs_border_solid_superellipse,
-+            cs_line_decoration,
-             cs_scale,
-             cs_svg_filter_node,
-             ps_text_run,
-             ps_text_run_dual_source,
-             ps_quad_textured,
-@@ -979,10 +997,12 @@
-     }
- 
-     pub fn cs_blur_rgba8(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_blur_rgba8) }
-     pub fn cs_border_segment(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_border_segment) }
-     pub fn cs_border_solid(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_border_solid) }
-+    pub fn cs_border_segment_superellipse(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_border_segment_superellipse) }
-+    pub fn cs_border_solid_superellipse(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_border_solid_superellipse) }
-     pub fn cs_line_decoration(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_line_decoration) }
-     pub fn cs_svg_filter_node(&mut self) -> &mut LazilyCompiledShader { self.loader.get(self.cs_svg_filter_node) }
-     pub fn ps_quad_textured(&mut self) -> &mut LazilyCompiledShader {
-         self.loader.get(self.ps_quad_textured)
-     }
-diff --git a/gfx/wr/webrender_build/src/shader_features.rs b/gfx/wr/webrender_build/src/shader_features.rs
---- a/gfx/wr/webrender_build/src/shader_features.rs
-+++ b/gfx/wr/webrender_build/src/shader_features.rs
-@@ -69,17 +69,22 @@
- 
-     shaders.insert("ps_quad_mask", vec![String::new(), "FAST_PATH".to_string(), "SUPERELLIPSE".to_string()]);
- 
-     for name in &[
-         "cs_line_decoration",
--        "cs_border_segment",
--        "cs_border_solid",
-         "cs_svg_filter_node",
-     ] {
-         shaders.insert(name, vec![String::new()]);
-     }
- 
-+    for name in &[
-+        "cs_border_segment",
-+        "cs_border_solid",
-+    ] {
-+        shaders.insert(name, vec![String::new(), "SUPERELLIPSE".to_string()]);
-+    }
-+
-     let mut base_prim_features = FeatureList::new();
- 
-     let mut texture_types = vec!["TEXTURE_2D"];
-     if flags.contains(ShaderFeatureFlags::GL) {
-         texture_types.push("TEXTURE_RECT");
-
diff --git a/src/external-patches/firefox/bug_2063169/D320211.patch b/src/external-patches/firefox/bug_2063169/D320211.patch
deleted file mode 100644
index 9cc3e6192..000000000
--- a/src/external-patches/firefox/bug_2063169/D320211.patch
+++ /dev/null
@@ -1,15 +0,0 @@
-diff --git a/devtools/client/responsive/test/browser/browser.toml b/devtools/client/responsive/test/browser/browser.toml
---- a/devtools/client/responsive/test/browser/browser.toml
-+++ b/devtools/client/responsive/test/browser/browser.toml
-@@ -275,7 +275,10 @@
- skip-if = [
-   "os == 'win' && os_version == '11.26100' && arch == 'x86_64' && asan", # Bug 2016837
- ]
- 
- ["browser_window_sizing.js"]
-+skip-if = [
-+  "os == 'win' && opt && standalone", # Bug 2063169
-+]
- 
- ["browser_zoom.js"]
-
diff --git a/src/external-patches/firefox/bug_2063169/D320568.patch b/src/external-patches/firefox/bug_2063169/D320568.patch
deleted file mode 100644
index 3002dd541..000000000
--- a/src/external-patches/firefox/bug_2063169/D320568.patch
+++ /dev/null
@@ -1,34 +0,0 @@
-diff --git a/layout/painting/nsDisplayList.cpp b/layout/painting/nsDisplayList.cpp
---- a/layout/painting/nsDisplayList.cpp
-+++ b/layout/painting/nsDisplayList.cpp
-@@ -4606,12 +4606,12 @@
-     wr::LayoutRect deviceClipRect = wr::ToLayoutRect(clipRect);
- 
-     nscoord spread = shadow.spread.ToAppUnits();
-     float spreadRadius = float(spread) / float(appUnitsPerDevPixel);
- 
--    wr::BorderRadius borderRadius{};
--    wr::BorderRadius shadowRadius{};
-+    wr::BorderRadius borderRadius = wr::EmptyBorderRadius();
-+    wr::BorderRadius shadowRadius = wr::EmptyBorderRadius();
-     if (hasBorderRadius) {
-       borderRadius = wr::ToBorderRadius(borderRadii);
-       if (spreadRadius) {
-         auto shadowRadii = borderRadii;
-         shadowRadii.AdjustOutwards(
-@@ -4727,12 +4727,12 @@
-         float(shadow.base.blur.ToAppUnits()) / float(appUnitsPerDevPixel);
- 
-     nscoord spread = shadow.spread.ToAppUnits();
-     float spreadRadius = spread / float(appUnitsPerDevPixel);
- 
--    wr::BorderRadius borderRadius{};
--    wr::BorderRadius shadowRadius{};
-+    wr::BorderRadius borderRadius = wr::EmptyBorderRadius();
-+    wr::BorderRadius shadowRadius = wr::EmptyBorderRadius();
-     if (hasBorderRadius) {
-       borderRadius = wr::ToBorderRadius(innerRadii);
-       if (spreadRadius) {
-         RectCornerRadii shadowRadii = innerRadii;
-         shadowRadii.AdjustInwards(
-
diff --git a/src/external-patches/firefox/bug_2063169/D321282.patch b/src/external-patches/firefox/bug_2063169/D321282.patch
deleted file mode 100644
index 06e44acc0..000000000
--- a/src/external-patches/firefox/bug_2063169/D321282.patch
+++ /dev/null
@@ -1,53 +0,0 @@
-diff --git a/gfx/wr/webrender/res/ps_quad_mask.glsl b/gfx/wr/webrender/res/ps_quad_mask.glsl
---- a/gfx/wr/webrender/res/ps_quad_mask.glsl
-+++ b/gfx/wr/webrender/res/ps_quad_mask.glsl
-@@ -318,12 +318,30 @@
-     #endif
- 
-     vec4 clip_dist =
-         mix(clip_rect, clip_rect.zwxy, lessThan(local_step, vec2(0.0)).xyxy)
-             - local_pos0.xyxy;
-+
-+    // Half-width, in local units, of the band around an edge over which
-+    // distance_aa() produces partial coverage.
-+    float aa_band = 0.5 * recip(aa_range);
-+    // An axis the span does not step along has the same distance to its two
-+    // edges for every pixel of the span, so the inside/outside test below
-+    // cannot resolve an edge that runs parallel to the span and coverage ends
-+    // up quantized to whole spans. Grow the rect by the AA band so that a span
-+    // landing inside the band counts as inside, which leaves the corner
-+    // selection below unchanged, and remember that the span is only partially
-+    // covered so the opaque run can be dropped further down.
-+    // `inset` is the distance from the span to the nearer of an axis' two
-+    // edges, positive when the span is between them.
-+    vec2 inset = min(-clip_dist.xy, clip_dist.zw);
-+    bvec2 flat_axis = equal(local_step, vec2(0.0));
-+    bvec2 partial = lessThan(inset, vec2(aa_band));
-+    bool aa_span = (flat_axis.x && partial.x) || (flat_axis.y && partial.y);
-+
-     clip_dist =
--        mix(1.0e6 * step(0.0, clip_dist),
-+        mix(1.0e6 * step(0.0, clip_dist - vec4(aa_band, aa_band, -aa_band, -aa_band)),
-             clip_dist * recip(local_step).xyxy,
-             notEqual(local_step, vec2(0.0)).xyxy);
- 
-     float opaque_start = max(clip_dist.x, clip_dist.y);
-     float opaque_end = min(clip_dist.z, clip_dist.w);
-@@ -404,10 +422,16 @@
- 
-     aa_margin = max(aa_margin - max(aa_start - aa_end, 0.0), 0.0);
-     aa_start -= aa_margin;
-     aa_end += aa_margin;
- 
-+    if (aa_span) {
-+        // No pixel of the span is fully covered, so collapse the opaque run and
-+        // let the anti-aliased runs on either side of it cover the whole span.
-+        opaque_end = min(opaque_end, opaque_start);
-+    }
-+
-     ivec4 steps = ivec4(clamp(
-         swgl_SpanLength -
-             swgl_StepSize *
-                 vec4(floor(aa_start), ceil(opaque_start), floor(opaque_end), ceil(aa_end)),
-         0.0, swgl_SpanLength));
-
diff --git a/src/external-patches/firefox/native_macos_popovers_fix.patch b/src/external-patches/firefox/native_macos_popovers_fix.patch
index d1aad1fa1..77821ff34 100644
--- a/src/external-patches/firefox/native_macos_popovers_fix.patch
+++ b/src/external-patches/firefox/native_macos_popovers_fix.patch
@@ -1,9 +1,8 @@
 diff --git a/toolkit/themes/shared/global-shared.css b/toolkit/themes/shared/global-shared.css
 --- a/toolkit/themes/shared/global-shared.css
 +++ b/toolkit/themes/shared/global-shared.css
-@@ -80,11 +80,10 @@
+@@ -80,10 +80,9 @@
      background-color: transparent;
-     --panel-background: transparent;
      --panel-box-shadow: none;
      --panel-border-color: transparent;
      --panel-box-shadow-margin: 0px;
diff --git a/src/external-patches/manifest.json b/src/external-patches/manifest.json
index 8491c0e4e..015ff6304 100644
--- a/src/external-patches/manifest.json
+++ b/src/external-patches/manifest.json
@@ -46,27 +46,11 @@
       "          jsonLengthHint,": "          lengthHint: jsonLengthHint,"
     }
   },
-  {
-    "type": "phabricator",
-    "id": "D320897",
-    "name": "Bug 2011236"
-  },
   {
     "type": "phabricator",
     "id": "D321446",
     "name": "Issue 14710"
   },
-  {
-    "type": "local",
-    // Sorts before bug_2063169/ on purpose: D319869 builds on the border
-    // shader hunks in here, and surfer applies patches in path order.
-    "path": "firefox/bug_2047627_corner_shape_borders.patch"
-  },
-  {
-    "type": "phabricator",
-    "ids": ["D319577", "D319796", "D319869", "D320211", "D320568", "D321282"],
-    "name": "Bug 2063169"
-  },
   {
     "type": "local",
     "path": "firefox/override_cert_checks_temp.patch"
diff --git a/src/layout/painting/nsImageRenderer-cpp.patch b/src/layout/painting/nsImageRenderer-cpp.patch
index 907df766d..565004eab 100644
--- a/src/layout/painting/nsImageRenderer-cpp.patch
+++ b/src/layout/painting/nsImageRenderer-cpp.patch
@@ -1,8 +1,8 @@
 diff --git a/layout/painting/nsImageRenderer.cpp b/layout/painting/nsImageRenderer.cpp
-index 6e464b48c90174b8954aad8a79bae30a7a30cbc9..9ea9a4963ceae679f092e014ac24a0d24fb106ce 100644
+index 7ddc4f7e259272e7b905f44aff7316c1ba540c22..277a92e5d10e6a04b12373854ffe6791d562215e 100644
 --- a/layout/painting/nsImageRenderer.cpp
 +++ b/layout/painting/nsImageRenderer.cpp
-@@ -90,7 +90,7 @@ static already_AddRefed<imgIContainer> GetSymbolicIconImage(nsAtom* aName,
+@@ -95,7 +95,7 @@ static already_AddRefed<imgIContainer> GetSymbolicIconImage(nsAtom* aName,
    if (NS_WARN_IF(!XRE_IsParentProcess())) {
      return nullptr;
    }
@@ -11,7 +11,7 @@ index 6e464b48c90174b8954aad8a79bae30a7a30cbc9..9ea9a4963ceae679f092e014ac24a0d2
    auto key = std::make_tuple(aName, aScale, fg);
    auto* cache = aFrame->GetOrCreateDeletableProperty(SymbolicImageCacheProp());
    auto lookup = cache->Lookup(key);
-@@ -575,7 +575,7 @@ ImgDrawResult nsImageRenderer::Draw(nsPresContext* aPresContext,
+@@ -580,7 +580,7 @@ ImgDrawResult nsImageRenderer::Draw(nsPresContext* aPresContext,
      }
      case StyleImage::Tag::Gradient: {
        nsCSSGradientRenderer renderer = nsCSSGradientRenderer::Create(
@@ -20,7 +20,7 @@ index 6e464b48c90174b8954aad8a79bae30a7a30cbc9..9ea9a4963ceae679f092e014ac24a0d2
  
        renderer.Paint(*ctx, aDest, aFill, aRepeatSize, aSrc, aDirtyRect,
                       aOpacity);
-@@ -652,7 +652,7 @@ ImgDrawResult nsImageRenderer::BuildWebRenderDisplayItems(
+@@ -657,7 +657,7 @@ ImgDrawResult nsImageRenderer::BuildWebRenderDisplayItems(
    switch (mType) {
      case StyleImage::Tag::Gradient: {
        nsCSSGradientRenderer renderer = nsCSSGradientRenderer::Create(
@@ -29,16 +29,16 @@ index 6e464b48c90174b8954aad8a79bae30a7a30cbc9..9ea9a4963ceae679f092e014ac24a0d2
  
        renderer.BuildWebRenderDisplayItems(aBuilder, aSc, aDest, aFill,
                                            aRepeatSize, aSrc,
-@@ -678,6 +678,8 @@ ImgDrawResult nsImageRenderer::BuildWebRenderDisplayItems(
-           nsPresContext::AppUnitsToIntCSSPixels(aDest.height)};
+@@ -679,6 +679,8 @@ ImgDrawResult nsImageRenderer::BuildWebRenderDisplayItems(
+       }
  
-       SVGImageContext svgContext(Some(destCSSSize));
+       SVGImageContext svgContext(Some(CSSSize::FromAppUnits(aDest.Size())));
 +      SVGImageContext::MaybeStoreZenBoosts(svgContext,
 +                                           *mForFrame->PresContext());
        Maybe<ImageIntRegion> region;
  
        const int32_t appUnitsPerDevPixel = aPresContext->AppUnitsPerDevPixel();
-@@ -1092,7 +1094,7 @@ ImgDrawResult nsImageRenderer::DrawShapeImage(nsPresContext* aPresContext,
+@@ -1098,7 +1100,7 @@ ImgDrawResult nsImageRenderer::DrawShapeImage(nsPresContext* aPresContext,
  
    if (mImage->IsGradient()) {
      nsCSSGradientRenderer renderer = nsCSSGradientRenderer::Create(
diff --git a/src/layout/svg/SVGGradientFrame-cpp.patch b/src/layout/svg/SVGGradientFrame-cpp.patch
index e2ce808c9..d3e65b8be 100644
--- a/src/layout/svg/SVGGradientFrame-cpp.patch
+++ b/src/layout/svg/SVGGradientFrame-cpp.patch
@@ -1,8 +1,8 @@
 diff --git a/layout/svg/SVGGradientFrame.cpp b/layout/svg/SVGGradientFrame.cpp
-index b0d38b0fab01797328af0b1f1f48af8fb5eebe4d..953feffdc96143dc2d8f8e57f8bb4a6aeb33f0c5 100644
+index eebcced86ec1e9010b761d5df4a92684dde44009..4dc018a73a979f50ac7842e4a3f3fcf9d0071b56 100644
 --- a/layout/svg/SVGGradientFrame.cpp
 +++ b/layout/svg/SVGGradientFrame.cpp
-@@ -229,8 +229,9 @@ class MOZ_STACK_CLASS SVGColorStopInterpolator
+@@ -228,8 +228,9 @@ class MOZ_STACK_CLASS SVGColorStopInterpolator
    SVGColorStopInterpolator(
        gfxPattern* aGradient, const nsTArray<ColorStop>& aStops,
        const StyleColorInterpolationMethod& aStyleColorInterpolationMethod,
@@ -14,8 +14,8 @@ index b0d38b0fab01797328af0b1f1f48af8fb5eebe4d..953feffdc96143dc2d8f8e57f8bb4a6a
          mGradient(aGradient) {}
  
    void CreateStop(float aPosition, DeviceColor aColor) {
-@@ -270,7 +271,8 @@ already_AddRefed<gfxPattern> SVGGradientFrame::GetPaintServerPattern(
-   if (nStops == 1 || GradientVectorLengthIsZero()) {
+@@ -269,7 +270,8 @@ already_AddRefed<gfxPattern> SVGGradientFrame::GetPaintServerPattern(
+   if (nStops == 1 || GradientVectorLengthIsZero(gradientUnits)) {
      // The gradient paints a single colour, using the stop-color of the last
      // gradient step if there are more than one.
 -    return MakeAndAddRef<gfxPattern>(ToDeviceColor(stops.LastElement().mColor));
diff --git a/src/layout/svg/SVGImageContext-h.patch b/src/layout/svg/SVGImageContext-h.patch
index fd225672e..fc5285d2f 100644
--- a/src/layout/svg/SVGImageContext-h.patch
+++ b/src/layout/svg/SVGImageContext-h.patch
@@ -1,5 +1,5 @@
 diff --git a/layout/svg/SVGImageContext.h b/layout/svg/SVGImageContext.h
-index ad833c7c2ee6a4c4984efdb0d59e3576c2d1bc19..36864a34badc0cbfe44d6295798622fd6178f9e3 100644
+index 63f3c4926cfdb8b12e9e4a38016fc66f50cf3129..5ba3f2c07f521905a086ee6eea87975d5a3441ec 100644
 --- a/layout/svg/SVGImageContext.h
 +++ b/layout/svg/SVGImageContext.h
 @@ -6,6 +6,7 @@
@@ -7,10 +7,10 @@ index ad833c7c2ee6a4c4984efdb0d59e3576c2d1bc19..36864a34badc0cbfe44d6295798622fd
  
  #include "Units.h"
 +#include "nsColor.h"
+ #include "mozilla/Casting.h"
  #include "mozilla/Maybe.h"
  #include "mozilla/SVGContextPaint.h"
- #include "mozilla/SVGPreserveAspectRatio.h"
-@@ -63,6 +64,11 @@ class SVGImageContext {
+@@ -64,6 +65,11 @@ class SVGImageContext {
                                       nsISVGPaintContext* aPaintContext,
                                       imgIContainer* aImgContainer);
  
@@ -19,10 +19,10 @@ index ad833c7c2ee6a4c4984efdb0d59e3576c2d1bc19..36864a34badc0cbfe44d6295798622fd
 +  static void MaybeStoreZenBoosts(SVGImageContext& aContext,
 +                                  const nsPresContext& aPresContext);
 +
-   const Maybe<CSSIntSize>& GetViewportSize() const { return mViewportSize; }
+   const Maybe<CSSSize>& GetViewportSize() const { return mViewportSize; }
  
-   void SetViewportSize(const Maybe<CSSIntSize>& aSize) {
-@@ -75,6 +81,21 @@ class SVGImageContext {
+   void SetViewportSize(const Maybe<CSSSize>& aSize) { mViewportSize = aSize; }
+@@ -74,6 +80,21 @@ class SVGImageContext {
      mColorScheme = aScheme;
    }
  
@@ -44,7 +44,7 @@ index ad833c7c2ee6a4c4984efdb0d59e3576c2d1bc19..36864a34badc0cbfe44d6295798622fd
    const Maybe<SVGPreserveAspectRatio>& GetPreserveAspectRatio() const {
      return mPreserveAspectRatio;
    }
-@@ -110,7 +131,11 @@ class SVGImageContext {
+@@ -109,7 +130,11 @@ class SVGImageContext {
      return contextPaintIsEqual && mViewportSize == aOther.mViewportSize &&
             mPreserveAspectRatio == aOther.mPreserveAspectRatio &&
             mColorScheme == aOther.mColorScheme &&
@@ -56,8 +56,8 @@ index ad833c7c2ee6a4c4984efdb0d59e3576c2d1bc19..36864a34badc0cbfe44d6295798622fd
 +           mZenBoostsInverted == aOther.mZenBoostsInverted;
    }
  
-   bool operator!=(const SVGImageContext&) const = default;
-@@ -123,7 +148,8 @@ class SVGImageContext {
+   PLDHashNumber Hash() const {
+@@ -120,7 +145,8 @@ class SVGImageContext {
      return AddToHash(hash, mViewportSize.map(HashSize).valueOr(0),
                       mPreserveAspectRatio.map(HashPAR).valueOr(0),
                       mColorScheme.map(HashColorScheme).valueOr(0),
@@ -67,7 +67,7 @@ index ad833c7c2ee6a4c4984efdb0d59e3576c2d1bc19..36864a34badc0cbfe44d6295798622fd
    }
  
   private:
-@@ -156,6 +182,9 @@ class SVGImageContext {
+@@ -154,6 +180,9 @@ class SVGImageContext {
    Maybe<SVGPreserveAspectRatio> mPreserveAspectRatio;
    Maybe<ColorScheme> mColorScheme;
    StyleLinkParameters mLinkParameters;
diff --git a/src/toolkit/content/widgets/panel-list/panel-list-mjs.patch b/src/toolkit/content/widgets/panel-list/panel-list-mjs.patch
deleted file mode 100644
index adde5f129..000000000
--- a/src/toolkit/content/widgets/panel-list/panel-list-mjs.patch
+++ /dev/null
@@ -1,29 +0,0 @@
-diff --git a/toolkit/content/widgets/panel-list/panel-list.mjs b/toolkit/content/widgets/panel-list/panel-list.mjs
-index 68ad2fafc8b31dfff541cf8381d9b9533e376d1c..fa62fec6bfb33338091fc06d3736fb76fd5c47c4 100644
---- a/toolkit/content/widgets/panel-list/panel-list.mjs
-+++ b/toolkit/content/widgets/panel-list/panel-list.mjs
-@@ -223,7 +223,12 @@ export class PanelList extends HTMLElement {
-     this.setAttribute("showing", "true");
-     // Tell the host element to hide any overflow in case the panel extends off
-     // the page before the alignment is set.
--    hostElement.style.overflow = "hidden";
-+    const hostHidesOverflow = !getComputedStyle(hostElement)
-+      .overflow.split(" ")
-+      .includes("visible");
-+    if (!hostHidesOverflow) {
-+      hostElement.style.overflow = "hidden";
-+    }
- 
-     // Wait for a layout flush, then find the bounds.
-     let {
-@@ -344,7 +349,9 @@ export class PanelList extends HTMLElement {
-       // Set the alignments and show the panel.
-       this.setAttribute("align", align);
-       this.setAttribute("valign", valign);
--      hostElement.style.overflow = "";
-+      if (!hostHidesOverflow) {
-+        hostElement.style.overflow = "";
-+      }
-       // Decide positioning based on where this panel will be rendered
-       const offsetParentIsBody =
-         this.supportsPopover() ||
diff --git a/src/toolkit/themes/shared/design-system/dist/tokens-shared-css.patch b/src/toolkit/themes/shared/design-system/dist/tokens-shared-css.patch
index f3da598d9..791607fef 100644
--- a/src/toolkit/themes/shared/design-system/dist/tokens-shared-css.patch
+++ b/src/toolkit/themes/shared/design-system/dist/tokens-shared-css.patch
@@ -1,5 +1,5 @@
 diff --git a/toolkit/themes/shared/design-system/dist/tokens-shared.css b/toolkit/themes/shared/design-system/dist/tokens-shared.css
-index 63c641f560d4c0ce06b40a652ca99d1c48cd6941..39c81e773a442870763396e68fb57bd336e3625a 100644
+index b0f8fa146de335c53e73d46853f45dda9b15cc73..1b7592c0e9ca12fd9d1f8a555633fd39c2efb537 100644
 --- a/toolkit/themes/shared/design-system/dist/tokens-shared.css
 +++ b/toolkit/themes/shared/design-system/dist/tokens-shared.css
 @@ -7,6 +7,8 @@
@@ -8,9 +8,9 @@ index 63c641f560d4c0ce06b40a652ca99d1c48cd6941..39c81e773a442870763396e68fb57bd3
  
 +@import url("chrome://browser/content/zen-styles/zen-theme.css");
 +
- @layer tokens-foundation {
-   :root,
-   :host(.anonymous-content-host) {
+ :root,
+ :host(.anonymous-content-host) {
+   @layer tokens-foundation {
 @@ -28,10 +30,10 @@
      --border-color-selected: var(--color-accent-primary);
      --border-color-transparent: transparent;
diff --git a/src/widget/cocoa/nsCocoaWindow-mm.patch b/src/widget/cocoa/nsCocoaWindow-mm.patch
index 983efe466..c5d39aae8 100644
--- a/src/widget/cocoa/nsCocoaWindow-mm.patch
+++ b/src/widget/cocoa/nsCocoaWindow-mm.patch
@@ -1,16 +1,17 @@
 diff --git a/widget/cocoa/nsCocoaWindow.mm b/widget/cocoa/nsCocoaWindow.mm
-index 2efd02e4a92433fd29bbfdb707aa81cfec45031e..3b763c3927f07e529c826f8e4f62bc80a324b247 100644
+index 887e4c052d5dd2b73d4c2059463529fb4b09dcab..36da18e19018b1b216576c299f938e75093546d3 100644
 --- a/widget/cocoa/nsCocoaWindow.mm
 +++ b/widget/cocoa/nsCocoaWindow.mm
-@@ -86,6 +86,7 @@
+@@ -86,6 +86,8 @@
  #include "mozilla/StaticPrefs_gfx.h"
  #include "mozilla/StaticPrefs_ui.h"
  #include "mozilla/StaticPrefs_widget.h"
 +#include "mozilla/StaticPrefs_zen.h"
++#include "mozilla/nsZenDragAndDrop.h"
  #include "mozilla/WritingModes.h"
  #include "mozilla/dom/Document.h"
  #include "mozilla/layers/CompositorBridgeChild.h"
-@@ -1332,6 +1333,110 @@ - (NSRect)_opaqueRectForWindowMoveWhenInTitlebar {
+@@ -1332,6 +1334,110 @@ - (NSRect)_opaqueRectForWindowMoveWhenInTitlebar {
  }
  @end
  
@@ -121,7 +122,28 @@ index 2efd02e4a92433fd29bbfdb707aa81cfec45031e..3b763c3927f07e529c826f8e4f62bc80
  void nsCocoaWindow::UpdateWindowDraggingRegion(
      const LayoutDeviceIntRegion& aRegion) {
    // mChildView returns YES from mouseDownCanMoveWindow, so we need to put
-@@ -4919,6 +5024,10 @@ - (BOOL)wantsBestResolutionOpenGLSurface {
+@@ -3858,7 +3964,9 @@ - (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender {
+ // NSDraggingDestination
+ - (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender {
+   MOZ_LOG(sCocoaLog, LogLevel::Info, ("ChildView draggingUpdated: entered\n"));
+-  return [self doDragAction:eDragOver sender:sender];
++  NSDragOperation operation = [self doDragAction:eDragOver sender:sender];
++  zen::PrepareDropLanding(sender);
++  return operation;
+ }
+ 
+ // NSDraggingDestination
+@@ -3874,6 +3982,9 @@ - (void)draggingExited:(id<NSDraggingInfo>)sender {
+ - (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
+   nsAutoRetainCocoaObject kungFuDeathGrip(self);
+   BOOL handled = [self doDragAction:eDrop sender:sender] != NSDragOperationNone;
++  if (handled) {
++    zen::LandDrop(sender);
++  }
+   NS_IF_RELEASE(mDragService);
+   return handled;
+ }
+@@ -4919,6 +5030,10 @@ - (BOOL)wantsBestResolutionOpenGLSurface {
  nsCocoaWindow::~nsCocoaWindow() {
    NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
  
diff --git a/src/widget/cocoa/nsDragService-mm.patch b/src/widget/cocoa/nsDragService-mm.patch
index 8308e701c..2ea44e90d 100644
--- a/src/widget/cocoa/nsDragService-mm.patch
+++ b/src/widget/cocoa/nsDragService-mm.patch
@@ -1,5 +1,5 @@
 diff --git a/widget/cocoa/nsDragService.mm b/widget/cocoa/nsDragService.mm
-index 340a9ad81c5cb23bb7e5f927d11d5cffdde7ce70..32fc707ccfa56fa8c307860868d092c4a9050419 100644
+index 340a9ad81c5cb23bb7e5f927d11d5cffdde7ce70..ba597ba4373ba3ace7455ce0859f2339349ffc06 100644
 --- a/widget/cocoa/nsDragService.mm
 +++ b/widget/cocoa/nsDragService.mm
 @@ -10,6 +10,7 @@
@@ -45,3 +45,112 @@ index 340a9ad81c5cb23bb7e5f927d11d5cffdde7ce70..32fc707ccfa56fa8c307860868d092c4
  #endif
        src += 4;
        dest += 4;
+@@ -249,12 +254,44 @@
+       [[[NSDraggingItem alloc] initWithPasteboardWriter:pbItem] autorelease];
+   [dragItem setDraggingFrame:localDragRect contents:image];
+ 
++  NSMutableArray* dragItems = [NSMutableArray arrayWithObject:dragItem];
++  auto zenDragAndDrop = zen::nsZenDragAndDrop::GetZenDragAndDropInstance();
++  const nsTArray<nsCOMPtr<nsINode>> noExtraImages;
++  @try {
++    for (const auto& extraImageNode :
++         zenDragAndDrop ? zenDragAndDrop->DragImages() : noExtraImages) {
++      nsCOMPtr<nsINode> mainImage = std::move(mImage);
++      mImage = extraImageNode;
++      NSPoint extraPoint;
++      NSImage* extraImage = ConstructDragImage(mSourceNode, aRegion, &extraPoint);
++      mImage = std::move(mainImage);
++      if (!extraImage) {
++        continue;
++      }
++      NSRect extraRect = extraImage.alignmentRect;
++      extraRect.origin.x = extraPoint.x;
++      extraRect.origin.y = extraPoint.y - extraRect.size.height;
++      NSPasteboardItem* extraPbItem = [[NSPasteboardItem new] autorelease];
++      [extraPbItem setData:[NSData data]
++                   forType:[UTIHelper stringFromPboardType:kMozWildcardPboardType]];
++      NSDraggingItem* extraItem = [[[NSDraggingItem alloc]
++          initWithPasteboardWriter:extraPbItem] autorelease];
++      [extraItem setDraggingFrame:extraRect contents:extraImage];
++      [dragItems addObject:extraItem];
++    }
++  } @catch (NSException* e) {
++    dragItems = [NSMutableArray arrayWithObject:dragItem];
++  }
++
+   OpenDragPopup();
+ 
+   mNSDraggingSession = [mNativeDragView
+-      beginDraggingSessionWithItems:[NSArray arrayWithObject:dragItem]
++      beginDraggingSessionWithItems:dragItems
+                               event:mNativeDragEvent
+                              source:mNativeDragView];
++  if (dragItems.count > 1) {
++    mNSDraggingSession.draggingFormation = NSDraggingFormationStack;
++  }
+ 
+   mNSDraggingSession.animatesToStartingPositionsOnCancelOrFail =
+       !mDataTransfer || mDataTransfer->MozShowFailAnimation();
+@@ -455,29 +492,44 @@
+     }
+ 
+     if (pc) {
++      nsPoint pt = LayoutDevicePixel::ToAppUnits(
++          devPoint, pc->DeviceContext()->AppUnitsPerDevPixel());
++      CSSIntPoint screenPoint =
++          CSSIntPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
++                      nsPresContext::AppUnitsToIntCSSPixels(pt.y));
++
++      NSMutableArray* images = [NSMutableArray array];
++      NSMutableArray* rects = [NSMutableArray array];
++      auto render = [&]() {
++        LayoutDeviceIntRect newRect;
++        NSImage* image =
++            ConstructDragImage(mSourceNode, Nothing(), screenPoint, &newRect);
++        [images addObject:image ? (id)image : (id)[NSNull null]];
++        [rects addObject:[NSValue valueWithRect:
++                                      image ? nsCocoaUtils::GeckoRectToCocoaRectDevPix(
++                                                  newRect, scaleFactor)
++                                            : NSZeroRect]];
++      };
++      render();
++      if (auto zenDragAndDrop = zen::nsZenDragAndDrop::GetZenDragAndDropInstance()) {
++        for (const auto& extraImageNode : zenDragAndDrop->DragImages()) {
++          nsCOMPtr<nsINode> mainImage = std::move(mImage);
++          mImage = extraImageNode;
++          render();
++          mImage = std::move(mainImage);
++        }
++      }
++
+       void (^changeImageBlock)(NSDraggingItem*, NSInteger, BOOL*) = ^(
+           NSDraggingItem* draggingItem, NSInteger idx, BOOL* stop) {
+-        // We never add more than one item right now, but check just in case.
+-        if (idx > 0) {
++        if ((NSUInteger)idx >= images.count || images[idx] == [NSNull null]) {
+           return;
+         }
+-
+-        nsPoint pt = LayoutDevicePixel::ToAppUnits(
+-            devPoint, pc->DeviceContext()->AppUnitsPerDevPixel());
+-        CSSIntPoint screenPoint =
+-            CSSIntPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
+-                        nsPresContext::AppUnitsToIntCSSPixels(pt.y));
+-
+-        // Create a new image; if one isn't returned don't change the current
+-        // one.
+-        LayoutDeviceIntRect newRect;
+-        NSImage* image =
+-            ConstructDragImage(mSourceNode, Nothing(), screenPoint, &newRect);
+-        if (image) {
+-          NSRect draggingRect =
+-              nsCocoaUtils::GeckoRectToCocoaRectDevPix(newRect, scaleFactor);
+-          [draggingItem setDraggingFrame:draggingRect contents:image];
++        NSRect frame = [rects[idx] rectValue];
++        if (idx > 0) {
++          frame.origin = draggingItem.draggingFrame.origin;
+         }
++        [draggingItem setDraggingFrame:frame contents:images[idx]];
+       };
+ 
+       [mNSDraggingSession
diff --git a/src/zen/common/modules/ZenUIManager.mjs b/src/zen/common/modules/ZenUIManager.mjs
index 935e82a43..4870deb16 100644
--- a/src/zen/common/modules/ZenUIManager.mjs
+++ b/src/zen/common/modules/ZenUIManager.mjs
@@ -1589,7 +1589,7 @@ window.gZenVerticalTabsManager = {
     gURLBar._initCopyCutController();
     gURLBar._initPasteAndGo();
     gURLBar._initStripOnShare();
-    gURLBar._updatePlaceholderFromDefaultEngine();
+    gURLBar.updatePlaceholder();
   },
 
   rebuildAreas() {
diff --git a/src/zen/common/styles/zen-panel-ui.css b/src/zen/common/styles/zen-panel-ui.css
index d9775692c..28ef2909a 100644
--- a/src/zen/common/styles/zen-panel-ui.css
+++ b/src/zen/common/styles/zen-panel-ui.css
@@ -32,6 +32,7 @@ panel[type="arrow"]:not(#feature-callout) {
 
   @media (-moz-platform: linux) or ((-moz-platform: windows) and (not (-moz-windows-mica-popups))) {
     &::part(content) {
+      /* stylelint-disable-next-line property-no-unknown */
       corner-shape: round; 
       border-radius: calc(var(--panel-border-radius) / var(--zen-squircle-value));
     }
diff --git a/src/zen/common/sys/ZenUIMigration.sys.mjs b/src/zen/common/sys/ZenUIMigration.sys.mjs
index 39ac96d47..38bca807d 100644
--- a/src/zen/common/sys/ZenUIMigration.sys.mjs
+++ b/src/zen/common/sys/ZenUIMigration.sys.mjs
@@ -7,7 +7,8 @@ import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
 });
 
 class nsZenUIMigration {
diff --git a/src/zen/common/zen-sets.js b/src/zen/common/zen-sets.js
index f62575840..fedaa580f 100644
--- a/src/zen/common/zen-sets.js
+++ b/src/zen/common/zen-sets.js
@@ -160,7 +160,7 @@ document.addEventListener(
           }
           case "cmd_zenDuplicateTab": {
             const selectedTabs = gBrowser.selectedTabs;
-            let insertAt = selectedTabs.at(-1)._tPos + 1;
+            let insertAt = selectedTabs.at(-1).index + 1;
             for (const tab of selectedTabs) {
               gBrowser.duplicateTab(tab, true, { tabIndex: insertAt++ });
             }
diff --git a/src/zen/drag-and-drop/ZenDragAndDrop.js b/src/zen/drag-and-drop/ZenDragAndDrop.js
index 87def6ded..f75ec69a1 100644
--- a/src/zen/drag-and-drop/ZenDragAndDrop.js
+++ b/src/zen/drag-and-drop/ZenDragAndDrop.js
@@ -27,7 +27,7 @@
    * - <tab-group> label element wrapper (.tab-group-label-container)
    *
    * When working with tab strip items, if you need logical information, you
-   * can get it directly, e.g. `element.elementIndex` or `element._tPos`. If
+   * can get it directly, e.g. `element.elementIndex` or `element._index`. If
    * you need spatial information like position or dimensions, then you should
    * call this function. For example, `elementToMove(element).getBoundingClientRect()`
    * or `elementToMove(element).style.top`.
@@ -69,6 +69,7 @@
     #changeSpaceTimer = null;
     #isAnimatingTabMove = false;
     #firstHapticFeedbackPlayed = false;
+    #dragImageEssential = false;
 
     #dragOverSplit = {};
 
@@ -152,10 +153,14 @@
       );
       const dragImage = this.#createDragImageForTabs(draggingTabs);
       this.originalDragImageArgs = [dragImage, offsetX, offsetY];
+      this.#dragImageEssential = tab.hasAttribute("zen-essential");
       dt.setDragImage(...this.originalDragImageArgs);
       if (tab.hasAttribute("zen-essential")) {
         tab.style.visibility = "hidden";
       }
+      this.ZenDragAndDropService.armDropLanding(
+        !args[0]?.fromTabList && this.getDropEffectForTabDrag(event) == "move"
+      );
     }
 
     #createDragImageForTabs(movingTabs) {
@@ -165,62 +170,79 @@
       const tabRect = window.windowUtils.getBoundsWithoutFlushing(
         movingTabs[0]
       );
+      const native = AppConstants.platform == "macosx";
+      const stacked = native ? 1 : Math.min(movingTabs.length, 3);
+      const wrapper = this.#createDragImageWrapper(periphery, tabRect, stacked);
+      for (let i = 0; i < stacked; i++) {
+        this.#appendDragImageClone(wrapper, movingTabs[i], tabRect, i);
+      }
+      this._dragImageTabs = native ? [...movingTabs] : [movingTabs[0]];
+      this._extraDragImages = [];
+      if (native) {
+        for (const tab of movingTabs.slice(1)) {
+          const extra = this.#createDragImageWrapper(periphery, tabRect, 1);
+          this.#appendDragImageClone(extra, tab, tabRect, 0);
+          this.ZenDragAndDropService.addDragImage(extra);
+          this._extraDragImages.push(extra);
+        }
+      } else {
+        this.#maybeCreateDragImageDot(movingTabs, wrapper);
+      }
+      this._tempDragImageParent = wrapper;
+      return wrapper;
+    }
+
+    #createDragImageWrapper(periphery, tabRect, count) {
       const wrapper = document.createElement("div");
-      let movingTabsCount = Math.min(movingTabs.length, 3);
       wrapper.style.width = tabRect.width + "px";
-      wrapper.style.height = tabRect.height * movingTabsCount + "px";
+      wrapper.style.height = tabRect.height * count + "px";
       wrapper.style.position = "fixed";
       wrapper.style.top = "-9999px";
       periphery.appendChild(wrapper);
-      for (let i = 0; i < movingTabsCount; i++) {
-        const tab = movingTabs[i];
-        const tabClone = tab.cloneNode(true);
-        if (tab.hasAttribute("zen-essential")) {
-          const rect = tab.getBoundingClientRect();
-          tabClone.style.minWidth = tabClone.style.maxWidth = `${rect.width}px`;
-          tabClone.style.minHeight =
-            tabClone.style.maxHeight = `${rect.height}px`;
-          if (tabClone.hasAttribute("visuallyselected")) {
-            tabClone.style.transform = "translate(-50%, -50%)";
-          }
-        } else if (AppConstants.platform == "win" && !tab.isZenFolder) {
-          // On windows, the shell applies its own translucency to the drag
-          // image which we can't control, so force some extra contrast for
-          // the tab to be more visible. This is a hacky workaround.
-          tabClone.style.colorScheme = "light";
-          tabClone.style.setProperty("--tab-selected-textcolor", "black");
+      return wrapper;
+    }
+
+    #appendDragImageClone(wrapper, tab, tabRect, i) {
+      const tabClone = tab.cloneNode(true);
+      if (tab.hasAttribute("zen-essential")) {
+        const rect = tab.getBoundingClientRect();
+        tabClone.style.minWidth = tabClone.style.maxWidth = `${rect.width}px`;
+        tabClone.style.minHeight =
+          tabClone.style.maxHeight = `${rect.height}px`;
+        if (tabClone.hasAttribute("visuallyselected")) {
+          tabClone.style.transform = "translate(-50%, -50%)";
         }
-        if (i > 0) {
-          tabClone.style.transform = `translate(${i * 4}px, -${i * (tabRect.height - 4)}px)`;
-          tabClone.style.opacity = "0.2";
-          tabClone.style.zIndex = `${-i}`;
-        }
-        tabClone.setAttribute("drag-image", "true");
-        wrapper.appendChild(tabClone);
-        if (isTab(tabClone)) {
-          // We need to limit the label content so the drag image doesn't grow too big.
-          const label = tabClone.textLabel;
-          const tabLabelParentWidth =
-            label.parentElement.getBoundingClientRect().width;
-          label.textContent = label.textContent.slice(
-            0,
-            Math.floor(tabLabelParentWidth / 6)
-          );
-        } else if (
-          gBrowser.isTabGroup(tabClone) &&
-          tabClone.hasAttribute("split-view-group")
-        ) {
-          let tabs = tab.tabs;
-          for (let j = 0; j < tabs.length; j++) {
-            const tabInGroup = tabs[j];
-            const tabInGroupClone = tabInGroup.cloneNode(true);
-            tabClone.appendChild(tabInGroupClone);
-          }
+      } else if (AppConstants.platform == "win" && !tab.isZenFolder) {
+        // On windows, the shell applies its own translucency to the drag
+        // image which we can't control, so force some extra contrast for
+        // the tab to be more visible. This is a hacky workaround.
+        tabClone.style.colorScheme = "light";
+        tabClone.style.setProperty("--tab-selected-textcolor", "black");
+      }
+      if (i > 0) {
+        tabClone.style.transform = `translate(${i * 4}px, -${i * (tabRect.height - 4)}px)`;
+        tabClone.style.opacity = "0.2";
+        tabClone.style.zIndex = `${-i}`;
+      }
+      tabClone.setAttribute("drag-image", "true");
+      wrapper.appendChild(tabClone);
+      if (isTab(tabClone)) {
+        // We need to limit the label content so the drag image doesn't grow too big.
+        const label = tabClone.textLabel;
+        const tabLabelParentWidth =
+          label.parentElement.getBoundingClientRect().width;
+        label.textContent = label.textContent.slice(
+          0,
+          Math.floor(tabLabelParentWidth / 6)
+        );
+      } else if (
+        gBrowser.isTabGroup(tabClone) &&
+        tabClone.hasAttribute("split-view-group")
+      ) {
+        for (const tabInGroup of tab.tabs) {
+          tabClone.appendChild(tabInGroup.cloneNode(true));
         }
       }
-      this.#maybeCreateDragImageDot(movingTabs, wrapper);
-      this._tempDragImageParent = wrapper;
-      return wrapper;
     }
 
     #maybeCreateDragImageDot(movingTabs, wrapper) {
@@ -255,7 +277,10 @@
           return;
         }
         return this.#animateVerticalPinnedGridDragOver(event);
-      } else if (this._fakeEssentialTab) {
+      } else if (
+        this.#dragImageEssential &&
+        !event.target.closest("zen-essentials-promo")
+      ) {
         this.#makeDragImageNonEssential(event);
       }
       let dragData = draggedTab._dragData;
@@ -557,7 +582,7 @@
           dropElementSize
         );
 
-        moveOverThreshold = gBrowser._tabGroupsEnabled
+        moveOverThreshold = gBrowser.tabGroupsEnabled
           ? Services.prefs.getIntPref(
               "browser.tabs.dragDrop.moveOverThresholdPercent"
             ) / 100
@@ -902,9 +927,54 @@
       }
       this.#isOutOfWindow = false;
       const dt = event.dataTransfer;
+      for (const extra of this._extraDragImages ?? []) {
+        this.#restoreExtraDragImage(extra);
+      }
       dt.updateDragImage(...this.originalDragImageArgs);
     }
 
+    /**
+     * Out of the window, every dragged tab becomes the window. Each further
+     * drag item gets a copy of the preview the drag image shows.
+     *
+     * @param {Element} extra - The image of a further tab
+     * @param {HTMLCanvasElement} canvas - The window preview
+     */
+    #previewExtraDragImage(extra, canvas) {
+      if (extra._tabContents) {
+        return;
+      }
+      extra._tabContents = {
+        nodes: [...extra.childNodes],
+        width: extra.style.width,
+        height: extra.style.height,
+      };
+      const copy = document.createElementNS(
+        "http://www.w3.org/1999/xhtml",
+        "canvas"
+      );
+      copy.width = canvas.width;
+      copy.height = canvas.height;
+      copy.getContext("2d").drawImage(canvas, 0, 0);
+      copy.style.width = copy.style.height = "100%";
+      copy.style.borderRadius = canvas.style.borderRadius;
+      copy.style.border = canvas.style.border;
+      extra.style.width = this._browserDragImageWrapper.style.width;
+      extra.style.height = this._browserDragImageWrapper.style.height;
+      extra.replaceChildren(copy);
+    }
+
+    #restoreExtraDragImage(extra) {
+      const contents = extra._tabContents;
+      if (!contents) {
+        return;
+      }
+      delete extra._tabContents;
+      extra.style.width = contents.width;
+      extra.style.height = contents.height;
+      extra.replaceChildren(...contents.nodes);
+    }
+
     handle_windowDragLeave(event) {
       // If relatedTarget exists, then we are still in the window
       if (
@@ -930,8 +1000,6 @@
       this.clearDragOverVisuals();
       this.clearSpaceSwitchTimer();
       const dt = event.dataTransfer;
-      let dragData = draggedTab._dragData;
-      let movingTabs = dragData.movingTabs;
       if (!this._browserDragImageWrapper) {
         const wrappingDiv = document.createXULElement("vbox");
         canvas.style.borderRadius = "8px";
@@ -939,11 +1007,13 @@
         wrappingDiv.style.width = 200 + "px";
         wrappingDiv.style.height = 130 + "px";
         wrappingDiv.style.position = "relative";
-        this.#maybeCreateDragImageDot(movingTabs, wrappingDiv);
         wrappingDiv.appendChild(canvas);
         this._browserDragImageWrapper = wrappingDiv;
         document.documentElement.appendChild(wrappingDiv);
       }
+      for (const extra of this._extraDragImages ?? []) {
+        this.#previewExtraDragImage(extra, canvas);
+      }
       dt.updateDragImage(
         this._browserDragImageWrapper,
         this.originalDragImageArgs[1],
@@ -975,6 +1045,45 @@
       this.#handle_dropSwitchSpace(event);
       this.#handle_dropCreateSplit(event);
       this._clearDragOverSplit();
+      this.#landDragImage(event);
+    }
+
+    /**
+     * Has the drag image land on the dropped tab rather than vanish. The OS
+     * slides it onto the tab's new place and ends the drag once it is there,
+     * which is when the tab shows again. Only macOS does so.
+     *
+     * @param {DragEvent} event - The drop
+     */
+    #landDragImage(event) {
+      // The drop is done, so its indicator goes before the image lands.
+      this.clearDragOverVisuals();
+      const draggedTab = event.dataTransfer.mozGetDataAt(TAB_DROP_TYPE, 0);
+      if (draggedTab?.documentGlobal !== window || gReduceMotion) {
+        return;
+      }
+      const elements = (this._dragImageTabs ?? [draggedTab])
+        .map(elementToMove)
+        .filter(element => element?.isConnected);
+      if (!elements.length) {
+        return;
+      }
+      for (const tab of this._dragImageTabs ?? [draggedTab]) {
+        const element = elementToMove(tab);
+        const rect = (
+          element?.isConnected ? element : elements[0]
+        ).getBoundingClientRect();
+        this.ZenDragAndDropService.addDropLandingRect(
+          Math.round(window.mozInnerScreenX + rect.left),
+          Math.round(window.mozInnerScreenY + rect.top),
+          Math.round(rect.width),
+          Math.round(rect.height)
+        );
+      }
+      for (const element of elements) {
+        element.style.visibility = "hidden";
+      }
+      this._landingElements = elements;
     }
 
     #handle_dropSwitchSpace(event) {
@@ -1175,6 +1284,10 @@
       let ownerGlobal = draggedTab?.documentGlobal;
       draggedTab.style.visibility = "";
       let thisFromGlobal = ownerGlobal?.gBrowser.tabContainer.tabDragAndDrop;
+      for (const element of thisFromGlobal._landingElements ?? []) {
+        element.style.visibility = "";
+      }
+      delete thisFromGlobal._landingElements;
       let currentEssenialContainer =
         ownerGlobal.gZenWorkspaces.getCurrentEssentialsContainer();
       if (currentEssenialContainer?.essentialsPromo) {
@@ -1211,6 +1324,11 @@
         thisFromGlobal._tempDragImageParent.remove();
         delete thisFromGlobal._tempDragImageParent;
       }
+      for (const extra of thisFromGlobal._extraDragImages ?? []) {
+        extra.remove();
+      }
+      delete thisFromGlobal._extraDragImages;
+      delete thisFromGlobal._dragImageTabs;
       delete ownerGlobal.gZenCompactModeManager._isTabBeingDragged;
       if (dt.dropEffect !== "move") {
         ownerGlobal.gZenCompactModeManager._clearAllHoverStates();
@@ -1494,6 +1612,7 @@
       switch (essentialsPromoStatus) {
         case "shown":
         case "created":
+          this.#makeDragImageEssential(event);
           return;
       }
 
@@ -1781,53 +1900,131 @@
     #makeDragImageEssential(event) {
       const dt = event.dataTransfer;
       const draggedTab = event.dataTransfer.mozGetDataAt(TAB_DROP_TYPE, 0);
-      if (draggedTab.hasAttribute("zen-essential")) {
+      if (this.#dragImageEssential) {
         return;
       }
+      this.#dragImageEssential = true;
       const dragData = draggedTab._dragData;
-      const [wrapper] = this.originalDragImageArgs;
-      const tab = wrapper.firstElementChild;
-      tab.setAttribute("zen-essential", "true");
-      tab.setAttribute("pinned", "true");
-      tab.setAttribute("selected", "true");
-      const draggedTabRect = window.windowUtils.getBoundsWithoutFlushing(
-        this._fakeEssentialTab
+      const wasEssential = draggedTab.hasAttribute("zen-essential");
+      const draggedTabRect = this.#essentialTileRect(event, draggedTab);
+      for (const { wrapper, tab } of this.#dragImageClones(draggedTab)) {
+        tab.setAttribute("zen-essential", "true");
+        tab.setAttribute("pinned", "true");
+        tab.setAttribute("selected", "true");
+        tab.style.minWidth =
+          tab.style.maxWidth =
+          wrapper.style.width =
+            draggedTabRect.width + "px";
+        tab.style.minHeight =
+          tab.style.maxHeight =
+          wrapper.style.height =
+            draggedTabRect.height + "px";
+        if (wasEssential) {
+          // Back to how the drag began.
+          tab.style.transform = "";
+          continue;
+        }
+        const offsetY = dragData.offsetY;
+        const offsetX = dragData.offsetX;
+        // Apply a transform translate to the tab in order to center it within the drag image
+        tab.style.transform = `translate(${(54 - offsetX) / 2}px, ${(50 - offsetY) / 2}px)`;
+        gZenPinnedTabManager.setEssentialTabIcon(tab);
+      }
+      if (wasEssential) {
+        dt.updateDragImage(...this.originalDragImageArgs);
+      } else {
+        dt.updateDragImage(this.originalDragImageArgs[0], -16, -16);
+      }
+    }
+
+    /**
+     * Every drag image with the tab it shows. The drag image itself and,
+     * on macOS, one for each further dragged tab.
+     *
+     * @param {Element} draggedTab
+     * @returns {{wrapper: Element, tab: Element, source: Element}[]} Each
+     *   image's wrapper, the clone in it, and the tab it was cloned from
+     */
+    #dragImageClones(draggedTab) {
+      const wrappers = [
+        this.originalDragImageArgs[0],
+        ...(this._extraDragImages ?? []),
+      ];
+      const sources = this._dragImageTabs ?? [draggedTab];
+      return wrappers.map((wrapper, i) => ({
+        wrapper,
+        tab: wrapper.firstElementChild,
+        source: sources[i] ?? draggedTab,
+      }));
+    }
+
+    /**
+     * The size the dragged tab takes as an essential. Its own when it is
+     * one, the tile made for it in the grid, or, with only the promo shown,
+     * a tile as the grid would lay it out.
+     *
+     * @param {DragEvent} event
+     * @param {Element} draggedTab
+     * @returns {{width: number, height: number}}
+     */
+    #essentialTileRect(event, draggedTab) {
+      const bounds = element =>
+        window.windowUtils.getBoundsWithoutFlushing(element);
+      if (draggedTab.hasAttribute("zen-essential")) {
+        return bounds(draggedTab);
+      }
+      if (this._fakeEssentialTab?.isConnected) {
+        return bounds(this._fakeEssentialTab);
+      }
+      const container =
+        event.target.closest(".zen-essentials-container") ??
+        gZenWorkspaces.getCurrentEssentialsContainer();
+      const height = parseFloat(
+        getComputedStyle(container).getPropertyValue("--tab-min-height")
       );
-      tab.style.minWidth =
-        tab.style.maxWidth =
-        wrapper.style.width =
-          draggedTabRect.width + "px";
-      tab.style.minHeight =
-        tab.style.maxHeight =
-        wrapper.style.height =
-          draggedTabRect.height + "px";
-      const offsetY = dragData.offsetY;
-      const offsetX = dragData.offsetX;
-      // Apply a transform translate to the tab in order to center it within the drag image
-      tab.style.transform = `translate(${(54 - offsetX) / 2}px, ${(50 - offsetY) / 2}px)`;
-      gZenPinnedTabManager.setEssentialTabIcon(tab);
-      dt.updateDragImage(wrapper, -16, -16);
+      return {
+        width: Math.max(bounds(container).width * 0.237, height + 4),
+        height,
+      };
     }
 
     #makeDragImageNonEssential(event) {
       const dt = event.dataTransfer;
       const draggedTab = event.dataTransfer.mozGetDataAt(TAB_DROP_TYPE, 0);
-      if (draggedTab.hasAttribute("zen-essential")) {
+      if (!this.#dragImageEssential) {
         return;
       }
-      const wrapper = this.originalDragImageArgs[0];
-      const tab = wrapper.firstElementChild;
-      tab.style.setProperty("transition", "none", "important");
-      tab.removeAttribute("zen-essential");
-      tab.removeAttribute("pinned");
-      tab.style.minWidth = tab.style.maxWidth = "";
-      tab.style.minHeight = tab.style.maxHeight = "";
-      tab.style.transform = "";
-      const rect = window.windowUtils.getBoundsWithoutFlushing(draggedTab);
-      wrapper.style.width = rect.width + "px";
-      wrapper.style.height = rect.height + "px";
+      this.#dragImageEssential = false;
+      // An essential takes the size of a row in the strip, as any tab there.
+      let model = draggedTab;
+      if (draggedTab.hasAttribute("zen-essential")) {
+        model =
+          this._tabbrowserTabs.ariaFocusableItems.find(
+            item => isTab(item) && !item.hasAttribute("zen-essential")
+          ) ?? draggedTab;
+      }
+      const rect = window.windowUtils.getBoundsWithoutFlushing(model);
+      const clones = this.#dragImageClones(draggedTab);
+      for (const { wrapper, tab, source } of clones) {
+        tab.style.setProperty("transition", "none", "important");
+        tab.removeAttribute("zen-essential");
+        tab.removeAttribute("pinned");
+        tab.style.minWidth = tab.style.maxWidth = "";
+        tab.style.minHeight = tab.style.maxHeight = "";
+        tab.style.transform = "";
+        wrapper.style.width = rect.width + "px";
+        wrapper.style.height = rect.height + "px";
+        if (source.hasAttribute("zen-essential") && tab.textLabel) {
+          tab.textLabel.textContent = source.label.slice(
+            0,
+            Math.floor(rect.width / 6)
+          );
+        }
+      }
       setTimeout(() => {
-        tab.style.transition = "";
+        for (const { tab } of clones) {
+          tab.style.transition = "";
+        }
         dt.updateDragImage(...this.originalDragImageArgs);
       }, 50);
     }
diff --git a/src/zen/drag-and-drop/moz.build b/src/zen/drag-and-drop/moz.build
index 19fa1df8c..ddf0c7c8b 100644
--- a/src/zen/drag-and-drop/moz.build
+++ b/src/zen/drag-and-drop/moz.build
@@ -16,7 +16,10 @@ SOURCES += [
 ]
 
 if CONFIG["MOZ_WIDGET_TOOLKIT"] == "cocoa":
-    SOURCES += ["nsZenNativeWindowMove.mm"]
+    SOURCES += [
+        "nsZenDropLandingCocoa.mm",
+        "nsZenNativeWindowMove.mm",
+    ]
 elif CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
     CXXFLAGS += CONFIG["MOZ_GTK3_CFLAGS"]
 
diff --git a/src/zen/drag-and-drop/nsIZenDragAndDrop.idl b/src/zen/drag-and-drop/nsIZenDragAndDrop.idl
index bc379458a..1ef8a3b1d 100644
--- a/src/zen/drag-and-drop/nsIZenDragAndDrop.idl
+++ b/src/zen/drag-and-drop/nsIZenDragAndDrop.idl
@@ -5,6 +5,7 @@
 #include "nsISupports.idl"
 
 interface mozIDOMWindowProxy;
+webidl Node;
 
 /**
  * @brief Interface for Zen's drag and drop functionality.
@@ -33,4 +34,24 @@ interface nsIZenDragAndDrop : nsISupports {
    * @param window The chrome window to move.
    */
   void beginNativeWindowMove(in mozIDOMWindowProxy window);
+
+  /**
+   * @brief Slide the drag image onto the drop instead of removing it.
+   * macOS only, the drag ends once it lands.
+   * @param arm Whether this drag's drops land the image.
+   */
+  void armDropLanding(in boolean arm);
+
+  /**
+   * @brief Drag an extra image along as its own item, one per further tab.
+   * macOS stacks and counts them. Add before the drag starts.
+   * @param image The element to render.
+   */
+  void addDragImage(in Node image);
+
+  /**
+   * @brief Where a drag item lands, in screen CSS pixels. One call per
+   * item in order, from within the drop event.
+   */
+  void addDropLandingRect(in long x, in long y, in long width, in long height);
 };
diff --git a/src/zen/drag-and-drop/nsZenDragAndDrop.cpp b/src/zen/drag-and-drop/nsZenDragAndDrop.cpp
index bc30f348b..0c7e6323e 100644
--- a/src/zen/drag-and-drop/nsZenDragAndDrop.cpp
+++ b/src/zen/drag-and-drop/nsZenDragAndDrop.cpp
@@ -91,9 +91,37 @@ nsZenDragAndDrop::OnDragStart(float opacity) {
 NS_IMETHODIMP
 nsZenDragAndDrop::OnDragEnd() {
   mDragImageOpacity = kZenDefaultDragImageOpacity;
+  mDropLandingArmed = false;
+  mDragImages.Clear();
+  mDropLandingRects.Clear();
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsZenDragAndDrop::ArmDropLanding(bool aArm) {
+  mDropLandingArmed = aArm;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsZenDragAndDrop::AddDragImage(nsINode* aImage) {
+  NS_ENSURE_ARG_POINTER(aImage);
+  mDragImages.AppendElement(aImage);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsZenDragAndDrop::AddDropLandingRect(int32_t aX, int32_t aY, int32_t aWidth,
+                                     int32_t aHeight) {
+  mDropLandingRects.AppendElement(
+      mozilla::DesktopIntRect(aX, aY, aWidth, aHeight));
+  return NS_OK;
+}
+
+nsTArray<mozilla::DesktopIntRect> nsZenDragAndDrop::TakeDropLandingRects() {
+  return std::move(mDropLandingRects);
+}
+
 NS_IMETHODIMP
 nsZenDragAndDrop::BeginNativeWindowMove(mozIDOMWindowProxy* aWindow) {
   NS_ENSURE_ARG_POINTER(aWindow);
diff --git a/src/zen/drag-and-drop/nsZenDragAndDrop.h b/src/zen/drag-and-drop/nsZenDragAndDrop.h
index 04dde7d26..cdcaab22c 100644
--- a/src/zen/drag-and-drop/nsZenDragAndDrop.h
+++ b/src/zen/drag-and-drop/nsZenDragAndDrop.h
@@ -7,6 +7,13 @@
 
 #include "nsIZenDragAndDrop.h"
 #include "nsCOMPtr.h"
+#include "Units.h"
+#include "nsINode.h"
+#include "nsTArray.h"
+
+#if defined(XP_MACOSX) && defined(__OBJC__)
+@protocol NSDraggingInfo;
+#endif
 
 #define ZEN_DND_MANAGER_CONTRACTID "@mozilla.org/zen/drag-and-drop;1"
 
@@ -26,6 +33,15 @@ class nsZenDragAndDrop final : public nsIZenDragAndDrop {
  public:
   explicit nsZenDragAndDrop();
   auto GetDragImageOpacity() const { return mDragImageOpacity; }
+  auto DropLandingArmed() const { return mDropLandingArmed; }
+  const auto& DragImages() const { return mDragImages; }
+
+  /**
+   * @brief Take the rects the drag items are to land on after the drop
+   * being handled, as the drop added them, in screen CSS pixels and item
+   * order. Empty when the drop added none.
+   */
+  nsTArray<mozilla::DesktopIntRect> TakeDropLandingRects();
 
   /**
    * @brief Get the singleton instance of nsZenDragAndDrop. There may be
@@ -39,8 +55,25 @@ class nsZenDragAndDrop final : public nsIZenDragAndDrop {
  private:
   ~nsZenDragAndDrop() = default;
   float mDragImageOpacity{};
+  bool mDropLandingArmed{};
+  nsTArray<nsCOMPtr<nsINode>> mDragImages;
+  nsTArray<mozilla::DesktopIntRect> mDropLandingRects;
 };
 
+#if defined(XP_MACOSX) && defined(__OBJC__)
+/**
+ * @brief From the drag destination view, once a dragover is handled, ask
+ * the OS to land the drag image on the drop, if the drag wants that.
+ */
+void PrepareDropLanding(id<NSDraggingInfo> aInfo);
+
+/**
+ * @brief From the drag destination view, once a drop is handled, send the
+ * drag image to the rect the drop set, if it set one.
+ */
+void LandDrop(id<NSDraggingInfo> aInfo);
+#endif
+
 }  // namespace zen
 
 #endif
diff --git a/src/zen/drag-and-drop/nsZenDropLandingCocoa.mm b/src/zen/drag-and-drop/nsZenDropLandingCocoa.mm
new file mode 100644
index 000000000..e822c6544
--- /dev/null
+++ b/src/zen/drag-and-drop/nsZenDropLandingCocoa.mm
@@ -0,0 +1,54 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#import <Cocoa/Cocoa.h>
+
+#include "nsCocoaUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsZenDragAndDrop.h"
+
+namespace zen {
+
+void PrepareDropLanding(id<NSDraggingInfo> aInfo) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  auto zen = nsZenDragAndDrop::GetZenDragAndDropInstance();
+  aInfo.animatesToDestination = zen && zen->DropLandingArmed();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void LandDrop(id<NSDraggingInfo> aInfo) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  auto zen = nsZenDragAndDrop::GetZenDragAndDropInstance();
+  if (!zen) {
+    return;
+  }
+  NSMutableArray* targets = [NSMutableArray array];
+  for (const auto& landing : zen->TakeDropLandingRects()) {
+    [targets
+        addObject:[NSValue valueWithRect:nsCocoaUtils::GeckoRectToCocoaRect(
+                                             landing)]];
+  }
+  if (!targets.count) {
+    return;
+  }
+  [aInfo enumerateDraggingItemsWithOptions:NSDraggingItemEnumerationConcurrent
+      forView:nil
+      classes:@[ [NSPasteboardItem class] ]
+      searchOptions:@{}
+      usingBlock:^(NSDraggingItem* item, NSInteger idx, BOOL* stop) {
+        NSRect target =
+            [targets[MIN((NSUInteger)idx, targets.count - 1)] rectValue];
+        NSRect frame = item.draggingFrame;
+        frame.origin.x = target.origin.x;
+        frame.origin.y = NSMaxY(target) - frame.size.height;
+        item.draggingFrame = frame;
+      }];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+}  // namespace zen
diff --git a/src/zen/folders/ZenFolders.mjs b/src/zen/folders/ZenFolders.mjs
index 1c27e5c6f..96df8ff93 100644
--- a/src/zen/folders/ZenFolders.mjs
+++ b/src/zen/folders/ZenFolders.mjs
@@ -327,7 +327,7 @@ class nsZenFolders extends nsZenDOMOperatedFeature {
     if (isActiveFolder) {
       for (const folder of group.activeGroups) {
         folder.activeTabs = [...new Set([...folder.activeTabs, tab])].sort(
-          (a, b) => a._tPos > b._tPos
+          (a, b) => a.index - b.index
         );
         this.setFolderIndentation([tab], folder, /* for collapse = */ true);
       }
@@ -378,7 +378,7 @@ class nsZenFolders extends nsZenDOMOperatedFeature {
     if (isActiveFolder && isSplitView) {
       parentFolder.activeTabs = [
         ...new Set([...parentFolder.activeTabs, ...folder.tabs]),
-      ].sort((a, b) => a._tPos > b._tPos);
+      ].sort((a, b) => a.index - b.index);
     }
     parentFolder.collapsed = isActiveFolder;
   }
@@ -1919,7 +1919,7 @@ class nsZenFolders extends nsZenDOMOperatedFeature {
               // It is important to keep the sequence of elements as in the DOM
               currentGroup.activeTabs = [
                 ...new Set([...currentGroup.activeTabs, ...activeTabs]),
-              ].sort((a, b) => a._tPos > b._tPos);
+              ].sort((a, b) => a.index - b.index);
             } else {
               currentGroup.setAttribute("has-active", "true");
               currentGroup.activeTabs = activeTabs;
diff --git a/src/zen/live-folders/ZenLiveFoldersManager.sys.mjs b/src/zen/live-folders/ZenLiveFoldersManager.sys.mjs
index 39f791b57..450b35d55 100644
--- a/src/zen/live-folders/ZenLiveFoldersManager.sys.mjs
+++ b/src/zen/live-folders/ZenLiveFoldersManager.sys.mjs
@@ -6,7 +6,8 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   JSONFile: "resource://gre/modules/JSONFile.sys.mjs",
   setTimeout: "resource://gre/modules/Timer.sys.mjs",
-  TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+  TabStateCache:
+    "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
   ZenWindowSync: "resource:///modules/zen/ZenWindowSync.sys.mjs",
   FeatureCallout: "resource:///modules/asrouter/FeatureCallout.sys.mjs",
 });
diff --git a/src/zen/sessionstore/ZenSessionManager.sys.mjs b/src/zen/sessionstore/ZenSessionManager.sys.mjs
index 4b883ef02..888cc586a 100644
--- a/src/zen/sessionstore/ZenSessionManager.sys.mjs
+++ b/src/zen/sessionstore/ZenSessionManager.sys.mjs
@@ -11,9 +11,12 @@ ChromeUtils.defineESModuleGetters(lazy, {
   ZenLiveFoldersManager:
     "resource:///modules/zen/ZenLiveFoldersManager.sys.mjs",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
-  SessionStartup: "resource:///modules/sessionstore/SessionStartup.sys.mjs",
-  TabStateFlusher: "resource:///modules/sessionstore/TabStateFlusher.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
+  SessionStartup:
+    "moz-src:///browser/components/sessionstore/SessionStartup.sys.mjs",
+  TabStateFlusher:
+    "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs",
   gWindowSyncEnabled: "resource:///modules/zen/ZenWindowSync.sys.mjs",
   gSyncOnlyPinnedTabs: "resource:///modules/zen/ZenWindowSync.sys.mjs",
   DeferredTask: "resource://gre/modules/DeferredTask.sys.mjs",
diff --git a/src/zen/sessionstore/ZenWindowSync.sys.mjs b/src/zen/sessionstore/ZenWindowSync.sys.mjs
index f19316ab4..832f07daa 100644
--- a/src/zen/sessionstore/ZenWindowSync.sys.mjs
+++ b/src/zen/sessionstore/ZenWindowSync.sys.mjs
@@ -10,13 +10,15 @@ const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
   BrowserWindowTracker: "resource:///modules/BrowserWindowTracker.sys.mjs",
-  TabStateFlusher: "resource:///modules/sessionstore/TabStateFlusher.sys.mjs",
+  TabStateFlusher:
+    "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs",
   // eslint-disable-next-line mozilla/valid-lazy
   ZenSessionStore: "resource:///modules/zen/ZenSessionManager.sys.mjs",
-  TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+  TabStateCache:
+    "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
   setTimeout: "resource://gre/modules/Timer.sys.mjs",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
-  RunState: "resource:///modules/sessionstore/RunState.sys.mjs",
+  RunState: "moz-src:///browser/components/sessionstore/RunState.sys.mjs",
 });
 
 XPCOMUtils.defineLazyPreferenceGetter(
diff --git a/src/zen/share/ZenShareManager.mjs b/src/zen/share/ZenShareManager.mjs
index ee5f6b78e..63d17490f 100644
--- a/src/zen/share/ZenShareManager.mjs
+++ b/src/zen/share/ZenShareManager.mjs
@@ -8,7 +8,8 @@ import { nsZenThemePicker } from "resource:///modules/zen/ZenGradientGenerator.m
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
-  TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+  TabStateCache:
+    "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
   ZenShareClient: "resource:///modules/zen/share/ZenShareClient.sys.mjs",
   ZenShareError: "resource:///modules/zen/share/ZenShareClient.sys.mjs",
 });
@@ -440,8 +441,8 @@ class nsZenShareManager extends nsZenDOMOperatedFeature {
         gZenUIManager.motion
           .animate(
             group,
-            { x: [-28, 0] },
-            { type: "spring", bounce: 0.9, duration: 1.4 }
+            { x: [-32, 0] },
+            { type: "spring", bounce: 0.5, duration: 1.5 }
           )
           .then(() => {
             group.style.removeProperty("transform");
diff --git a/src/zen/spaces/ZenSpaceManager.mjs b/src/zen/spaces/ZenSpaceManager.mjs
index e7e57a67a..5d34b6d05 100644
--- a/src/zen/spaces/ZenSpaceManager.mjs
+++ b/src/zen/spaces/ZenSpaceManager.mjs
@@ -1773,10 +1773,10 @@ class nsZenWorkspaces {
     if (this.tabContainer) {
       this.tabContainer._invalidateCachedTabs();
     }
-    // Fix tabs _tPos values relative to the actual order
+    // Fix tabs _index values relative to the actual order
     const tabs = gBrowser.tabs;
     const usedGroups = new Set();
-    let tPos = 0; // _tPos is used for the session store, not needed for folders
+    let tPos = 0; // _index is used for the session store, not needed for folders
     let pPos = 0; // _pPos is used for the pinned tabs manager
     const recurseFolder = tab => {
       if (tab.group) {
@@ -1789,7 +1789,7 @@ class nsZenWorkspaces {
     };
     for (const tab of tabs) {
       recurseFolder(tab);
-      tab._tPos = tPos++;
+      tab._index = tPos++;
       if (!tab.hasAttribute("zen-empty-tab")) {
         tab._pPos = pPos++;
       }
diff --git a/src/zen/spaces/zen-workspaces.css b/src/zen/spaces/zen-workspaces.css
index 3ba336407..ed03244ad 100644
--- a/src/zen/spaces/zen-workspaces.css
+++ b/src/zen/spaces/zen-workspaces.css
@@ -352,6 +352,8 @@ zen-workspace {
       scrollbar-width: auto;
       scrollbar-color: color-mix(in srgb, currentColor 35%, transparent 65%) transparent; /* Custom scrollbar */
       overflow-y: auto;
+      padding-block-end: 120px;
+      overscroll-behavior: auto;
     }
 
     :root[swipe-gesture] &::part(scrollbox) {
diff --git a/src/zen/split-view/ZenViewSplitter.mjs b/src/zen/split-view/ZenViewSplitter.mjs
index 9f6274151..67ded7b24 100644
--- a/src/zen/split-view/ZenViewSplitter.mjs
+++ b/src/zen/split-view/ZenViewSplitter.mjs
@@ -1601,7 +1601,7 @@ class nsZenViewSplitter extends nsZenDOMOperatedFeature {
       tab.hasAttribute("pending")
     );
     if (pendingTabs.length) {
-      pendingTabs.forEach(tab => gBrowser._insertBrowser(tab));
+      pendingTabs.forEach(tab => gBrowser.insertBrowser(tab));
       // SessionStore listens for this on the tab container and restores each
       // tab's saved history, scroll position and form data. Kept non-bubbling
       // so it doesn't reach tabbrowser, which tracks Firefox's own split view.
diff --git a/src/zen/sync/ZenSpacesSyncApplier.sys.mjs b/src/zen/sync/ZenSpacesSyncApplier.sys.mjs
index 107f610e0..118fc7f81 100644
--- a/src/zen/sync/ZenSpacesSyncApplier.sys.mjs
+++ b/src/zen/sync/ZenSpacesSyncApplier.sys.mjs
@@ -23,10 +23,13 @@ XPCOMUtils.defineLazyPreferenceGetter(
 );
 
 ChromeUtils.defineESModuleGetters(lazy, {
-  SessionSaver: "resource:///modules/sessionstore/SessionSaver.sys.mjs",
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+  SessionSaver:
+    "moz-src:///browser/components/sessionstore/SessionSaver.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
   E10SUtils: "resource://gre/modules/E10SUtils.sys.mjs",
-  TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+  TabStateCache:
+    "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
   ZenWindowSync: "resource:///modules/zen/ZenWindowSync.sys.mjs",
   ZenLiveFoldersManager:
     "resource:///modules/zen/ZenLiveFoldersManager.sys.mjs",
diff --git a/src/zen/tabs/ZenPinnedTabManager.mjs b/src/zen/tabs/ZenPinnedTabManager.mjs
index e8d84a1ef..99823367d 100644
--- a/src/zen/tabs/ZenPinnedTabManager.mjs
+++ b/src/zen/tabs/ZenPinnedTabManager.mjs
@@ -34,7 +34,8 @@ class ZenPinnedTabsObserver {
     ChromeUtils.defineESModuleGetters(lazy, {
       // eslint-disable-next-line mozilla/valid-lazy
       E10SUtils: "resource://gre/modules/E10SUtils.sys.mjs",
-      TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+      TabStateCache:
+        "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
     });
     this.#listenPinnedTabEvents();
   }
diff --git a/src/zen/tabs/zen-tabs/vertical-tabs.css b/src/zen/tabs/zen-tabs/vertical-tabs.css
index d53bcd1f1..471b17aaa 100644
--- a/src/zen/tabs/zen-tabs/vertical-tabs.css
+++ b/src/zen/tabs/zen-tabs/vertical-tabs.css
@@ -329,6 +329,10 @@
       display: none;
     }
 
+    &[drag-image] {
+      border-radius: calc(var(--border-radius-medium) / var(--zen-squircle-value));
+    }
+
     /* stylelint-disable-next-line stylelint-plugin-mozilla/no-has-selector */
     :root:not([zen-renaming-tab="true"])
     #tabbrowser-tabs:not([movingtab])
@@ -1268,10 +1272,6 @@
     left: calc(var(--indicator-left) + 2 * var(--zen-drag-indicator-height) + 4px);
     width: calc(var(--indicator-width) - 2 * var(--zen-drag-indicator-height) - 4px);
     height: var(--zen-drag-indicator-height);
-    transition:
-      top 0.05s ease-out,
-      left 0.05s ease-out,
-      width 0.05s ease-out;
 
     &::before {
       left: calc(-2 * var(--zen-drag-indicator-height));
@@ -1284,10 +1284,6 @@
     top: calc(var(--indicator-top) + 2 * var(--zen-drag-indicator-height) + 4px);
     height: calc(var(--indicator-height) - 2 * var(--zen-drag-indicator-height) - 4px);
     width: var(--zen-drag-indicator-height);
-    transition:
-      top 0.1s ease-out,
-      left 0.1s ease-out,
-      height 0.1s ease-out;
 
     &::before {
       top: calc(-2 * var(--zen-drag-indicator-height));
diff --git a/src/zen/tests/device_sync/head.js b/src/zen/tests/device_sync/head.js
index 46a445c52..bb77057ed 100644
--- a/src/zen/tests/device_sync/head.js
+++ b/src/zen/tests/device_sync/head.js
@@ -11,10 +11,10 @@ const { ZenSpacesSyncApplier } = ChromeUtils.importESModule(
   "resource:///modules/zen/ZenSpacesSyncApplier.sys.mjs"
 );
 const { SessionSaver } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionSaver.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionSaver.sys.mjs"
 );
 const { TabStateFlusher } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+  "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
 );
 const { TestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/TestUtils.sys.mjs"
diff --git a/src/zen/tests/folders/browser_folder_issue_9981.js b/src/zen/tests/folders/browser_folder_issue_9981.js
index 3f035c2d0..13ec5da87 100644
--- a/src/zen/tests/folders/browser_folder_issue_9981.js
+++ b/src/zen/tests/folders/browser_folder_issue_9981.js
@@ -44,8 +44,16 @@ add_task(async function test_Issue_9981() {
 
   const tab2ResetButton = tab2.querySelector(".tab-reset-button");
   tab2ResetButton.style.display = "flex";
+  await TestUtils.waitForCondition(
+    () => tab2ResetButton.getBoundingClientRect().width != 0
+  );
   EventUtils.synthesizeMouseAtCenter(tab2ResetButton, {});
 
+  await TestUtils.waitForCondition(
+    () => !tab2.hasAttribute("folder-active"),
+    "Tab 2 should be unloaded out of the active folder"
+  );
+
   ok(
     tab1.hasAttribute("folder-active"),
     "Tab 1 should be in the active folder"
diff --git a/src/zen/tests/glance/browser_glance_expand.js b/src/zen/tests/glance/browser_glance_expand.js
index 74c3ca660..efc1d8b18 100644
--- a/src/zen/tests/glance/browser_glance_expand.js
+++ b/src/zen/tests/glance/browser_glance_expand.js
@@ -17,8 +17,8 @@ add_task(async function test_Glance_Basic_Open() {
       "There should be no zen-glance-tab attribute on any tab"
     );
     Assert.greater(
-      glanceTab._tPos,
-      selectedTab._tPos,
+      glanceTab.index,
+      selectedTab.index,
       "The glance tab should be on the right of the selected tab"
     );
     BrowserTestUtils.removeTab(glanceTab);
@@ -42,8 +42,8 @@ add_task(async function test_Glance_Open_Sibling() {
   await openGlanceOnTab(async glanceTab => {
     await gZenGlanceManager.fullyOpenGlance();
     Assert.equal(
-      glanceTab._tPos,
-      selectedTab._tPos + 1,
+      glanceTab._index,
+      selectedTab._index + 1,
       "The glance tab should be on the right of the selected tab"
     );
     BrowserTestUtils.removeTab(glanceTab);
diff --git a/src/zen/tests/glance/browser_glance_select_parent.js b/src/zen/tests/glance/browser_glance_select_parent.js
index 48a519419..cc351d773 100644
--- a/src/zen/tests/glance/browser_glance_select_parent.js
+++ b/src/zen/tests/glance/browser_glance_select_parent.js
@@ -19,7 +19,7 @@ add_task(async function test_Glance_Select_Parent() {
     );
     const tabToRemove = gBrowser.selectedTab;
     gBrowser.selectedTab = gZenGlanceManager.getTabOrGlanceParent(glanceTab);
-    await BrowserTestUtils.waitForCondition(() => {
+    await TestUtils.waitForCondition(() => {
       return glanceTab.selected;
     });
     ok(true, "The glance tab should be selected");
diff --git a/src/zen/tests/manifest.toml b/src/zen/tests/manifest.toml
index c01ed3e6c..65094720e 100644
--- a/src/zen/tests/manifest.toml
+++ b/src/zen/tests/manifest.toml
@@ -146,6 +146,12 @@ xpcshell = true
 source = "browser/components/tabbrowser/test/browser/tabMediaIndicator"
 is_direct_path = true
 
+[tabMediaIndicator.replace-manifest]
+"[DEFAULT]" = """[DEFAULT]
+prefs = [
+  "zen.window-sync.enabled=false",
+]"""
+
 [tooltiptext]
 source = "toolkit/components/tooltiptext"
 disable = [
diff --git a/src/zen/tests/media/browser_media_metadata.js b/src/zen/tests/media/browser_media_metadata.js
index 281ec151b..dad1b4c3b 100644
--- a/src/zen/tests/media/browser_media_metadata.js
+++ b/src/zen/tests/media/browser_media_metadata.js
@@ -21,7 +21,7 @@ add_task(async function test_media_bar_shows_metadata_from_page() {
     const titleEl = card.querySelector(".zen-media-title");
     const artistEl = card.querySelector(".zen-media-artist");
 
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => titleEl.textContent === "Sandstorm",
       "title label reflects the page's mediaSession metadata"
     );
@@ -36,7 +36,7 @@ add_task(async function test_media_bar_shows_metadata_from_page() {
       title: "Levels",
       artist: "Avicii",
     });
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => titleEl.textContent === "Levels",
       "title updates live when the page changes its mediaSession metadata"
     );
diff --git a/src/zen/tests/media/browser_media_mute.js b/src/zen/tests/media/browser_media_mute.js
index 68e0dda02..e9d3b562b 100644
--- a/src/zen/tests/media/browser_media_mute.js
+++ b/src/zen/tests/media/browser_media_mute.js
@@ -24,7 +24,7 @@ add_task(async function test_mute_from_media_bar() {
     );
 
     clickMediaButton("zen-media-mute-button");
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => mediaTab.linkedBrowser.audioMuted,
       "tab becomes muted after clicking the media bar mute button"
     );
@@ -34,7 +34,7 @@ add_task(async function test_mute_from_media_bar() {
     );
 
     clickMediaButton("zen-media-mute-button");
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => !mediaTab.linkedBrowser.audioMuted,
       "clicking again unmutes the tab"
     );
diff --git a/src/zen/tests/media/browser_media_next_track.js b/src/zen/tests/media/browser_media_next_track.js
index dd6804d15..82ac13528 100644
--- a/src/zen/tests/media/browser_media_next_track.js
+++ b/src/zen/tests/media/browser_media_next_track.js
@@ -21,7 +21,7 @@ add_task(async function test_next_track_relays_to_page() {
 
     // supportedkeyschange propagates asynchronously; wait for the bar's
     // next-track button to become enabled before clicking.
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => !nextButton.disabled,
       "next-track button becomes enabled once the page registers a handler"
     );
diff --git a/src/zen/tests/media/browser_media_shows_on_tab_switch.js b/src/zen/tests/media/browser_media_shows_on_tab_switch.js
index d6f5a92ee..58a1b63bb 100644
--- a/src/zen/tests/media/browser_media_shows_on_tab_switch.js
+++ b/src/zen/tests/media/browser_media_shows_on_tab_switch.js
@@ -5,7 +5,7 @@
 
 add_task(async function test_media_bar_shows_when_switching_off_playing_tab() {
   gZenMediaController.closeAllCards();
-  await BrowserTestUtils.waitForCondition(
+  await TestUtils.waitForCondition(
     () => !isMediaBarVisible(),
     "media bar hides again once the playing tab regains focus"
   );
@@ -31,7 +31,7 @@ add_task(async function test_media_bar_shows_when_switching_off_playing_tab() {
     // timer; wait for the visibility flip rather than racing it.
     await BrowserTestUtils.switchTab(gBrowser, originalTab);
     await new Promise(r => setTimeout(r, 1000));
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       isMediaBarVisible,
       "media bar becomes visible after switching off the playing tab"
     );
@@ -44,7 +44,7 @@ add_task(async function test_media_bar_shows_when_switching_off_playing_tab() {
 
     await BrowserTestUtils.switchTab(gBrowser, mediaTab);
     await new Promise(r => setTimeout(r, 1000));
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => !isMediaBarVisible(),
       "media bar hides again once the playing tab regains focus"
     );
diff --git a/src/zen/tests/media/browser_media_stack.js b/src/zen/tests/media/browser_media_stack.js
index 07d3b0cf0..459c4b3a8 100644
--- a/src/zen/tests/media/browser_media_stack.js
+++ b/src/zen/tests/media/browser_media_stack.js
@@ -21,7 +21,7 @@ add_task(async function test_media_stack_shows_multiple_cards() {
     await waitForMediaBarVisible();
 
     // Cards reappear on the 500ms tab-switch debounce; wait for both.
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => visibleMediaCards().length === 2,
       "both playing tabs get their own card in the stack"
     );
@@ -32,7 +32,7 @@ add_task(async function test_media_stack_shows_multiple_cards() {
       "front card belongs to the most recently started media"
     );
 
-    await BrowserTestUtils.waitForCondition(() => {
+    await TestUtils.waitForCondition(() => {
       const titles = visibleMediaCards().map(
         card => card.querySelector(".zen-media-title").textContent
       );
@@ -41,7 +41,7 @@ add_task(async function test_media_stack_shows_multiple_cards() {
 
     // Closing the front card only removes that session.
     clickMediaButton("zen-media-close-button");
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => visibleMediaCards().length === 1,
       "closing the front card only removes that card"
     );
diff --git a/src/zen/tests/media/head.js b/src/zen/tests/media/head.js
index 50dfaa974..c8f2f4f80 100644
--- a/src/zen/tests/media/head.js
+++ b/src/zen/tests/media/head.js
@@ -31,7 +31,7 @@ async function playVideoIn(tab) {
   );
   // Wait for the browser to actually consider the tab "playing" — this is
   // what drives the soundplaying TabAttrModified into the media controller.
-  await BrowserTestUtils.waitForCondition(
+  await TestUtils.waitForCondition(
     () => tab.soundPlaying,
     "tab reports soundplaying"
   );
@@ -57,7 +57,7 @@ function isMediaBarVisible() {
 }
 
 async function waitForMediaBarVisible() {
-  await BrowserTestUtils.waitForCondition(
+  await TestUtils.waitForCondition(
     isMediaBarVisible,
     "media bar becomes visible"
   );
diff --git a/src/zen/tests/mochitests/sessionstore/SessionStoreTestUtils.sys.mjs b/src/zen/tests/mochitests/sessionstore/SessionStoreTestUtils.sys.mjs
index 889245172..3105aed51 100644
--- a/src/zen/tests/mochitests/sessionstore/SessionStoreTestUtils.sys.mjs
+++ b/src/zen/tests/mochitests/sessionstore/SessionStoreTestUtils.sys.mjs
@@ -1,8 +1,10 @@
 const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   BrowserTestUtils: "resource://testing-common/BrowserTestUtils.sys.mjs",
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
-  TabStateFlusher: "resource:///modules/sessionstore/TabStateFlusher.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
+  TabStateFlusher:
+    "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs",
   TestUtils: "resource://testing-common/TestUtils.sys.mjs",
 });
 
@@ -89,7 +91,7 @@ export var SessionStoreTestUtils = {
       "browser.sessionstore.restore_hidden_tabs"
     );
     // This should match the |restoreTabsLazily| value that
-    // SessionStore.restoreWindow() uses.
+    // SessionStore's #restoreWindow() uses.
     let restoreTabsLazily =
       Services.prefs.getBoolPref("browser.sessionstore.restore_on_demand") &&
       Services.prefs.getBoolPref("browser.sessionstore.restore_tabs_lazily");
diff --git a/src/zen/tests/mochitests/sessionstore/browser.toml b/src/zen/tests/mochitests/sessionstore/browser.toml
index d49574a0e..6f6f10b6f 100644
--- a/src/zen/tests/mochitests/sessionstore/browser.toml
+++ b/src/zen/tests/mochitests/sessionstore/browser.toml
@@ -293,6 +293,8 @@ disabled="Disabled by import_external_tests.py"
 ["browser_restore_redirect.js"]
 https_first_disabled = true
 
+["browser_restore_respects_pending_minimize.js"]
+
 ["browser_restore_reversed_z_order.js"]
 skip-if = [
   "true", # Bug 1455602
@@ -355,7 +357,7 @@ skip-if = [
 
 ["browser_sizemodeBeforeMinimized.js"]
 skip-if = [
-  "os == 'linux' && os_version == '22.04' && arch == 'x86_64' && opt && nova", # Bug 2057856
+  "os == 'linux' && os_version == '22.04' && arch == 'x86_64'", # Bug 2057856
   "os == 'win' && os_version == '11.26200' && asan", # Bug 2019745
 ]
 
diff --git a/src/zen/tests/mochitests/sessionstore/browser_1284886_suspend_tab.js b/src/zen/tests/mochitests/sessionstore/browser_1284886_suspend_tab.js
index 3c6a2c1f2..e7e4f2df4 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_1284886_suspend_tab.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_1284886_suspend_tab.js
@@ -3,7 +3,12 @@
 
 add_task(async function test() {
   await SpecialPowers.pushPrefEnv({
-    set: [["dom.require_user_interaction_for_beforeunload", false]],
+    set: [
+      ["dom.require_user_interaction_for_beforeunload", false],
+      // Keep the tab closing animation, which this test relies on to observe
+      // a tab in its closing state.
+      ["ui.prefersReducedMotion", 0],
+    ],
   });
 
   let url = "about:robots";
@@ -37,12 +42,15 @@ add_task(async function test() {
   ok(tab0.linkedPanel, "active tab is not able to be suspended");
 
   // Test that tab that is closing is not able to be suspended.
-  gBrowser._beginRemoveTab(tab1);
+  gBrowser.removeTab(tab1, { animate: true });
   gBrowser.discardBrowser(tab1);
 
   ok(tab1.linkedPanel, "cannot suspend a tab that is closing");
 
-  gBrowser._endRemoveTab(tab1);
+  await TestUtils.waitForCondition(
+    () => !tab1.isConnected,
+    "tab1 finished closing"
+  );
 
   // Open tab containing a page which has a beforeunload handler which shows a prompt.
   url =
diff --git a/src/zen/tests/mochitests/sessionstore/browser_495495.js b/src/zen/tests/mochitests/sessionstore/browser_495495.js
index 1bb2d1133..84f1d868d 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_495495.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_495495.js
@@ -17,7 +17,7 @@ add_task(async function test_urlbarFocus() {
   newWin = openDialog(
     location,
     "_blank",
-    "chrome,extrachrome,menubar,resizable,scrollbars,status,toolbar=no,location,personal,directories,dialog=no"
+    "chrome,resizable,toolbar=no,dialog=no"
   );
   await promiseWindowLoaded(newWin);
   let state2 = ss.getWindowState(newWin);
diff --git a/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_duplicateTab.js b/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_duplicateTab.js
index a94b056f5..9213c3844 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_duplicateTab.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_duplicateTab.js
@@ -64,6 +64,6 @@ function test_duplicateTab() {
   window.addEventListener("SSWindowStateReady", onSSWindowStateReady);
   gBrowser.tabContainer.addEventListener("SSTabRestoring", onSSTabRestoring);
 
-  gBrowser._insertBrowser(tab);
+  gBrowser.insertBrowser(tab);
   newTab = ss.duplicateTab(window, tab);
 }
diff --git a/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_setTabState.js b/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_setTabState.js
index 99ada805b..217c07d4e 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_setTabState.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_615394-SSWindowState_events_setTabState.js
@@ -56,6 +56,6 @@ function test_setTabState() {
   window.addEventListener("SSWindowStateReady", onSSWindowStateReady);
   tab.addEventListener("SSTabRestoring", onSSTabRestoring, { once: true });
   // Browser must be inserted in order to restore.
-  gBrowser._insertBrowser(tab);
+  gBrowser.insertBrowser(tab);
   ss.setTabState(tab, newTabState);
 }
diff --git a/src/zen/tests/mochitests/sessionstore/browser_906076_lazy_tabs.js b/src/zen/tests/mochitests/sessionstore/browser_906076_lazy_tabs.js
index 2fab82ca0..f1f95ae45 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_906076_lazy_tabs.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_906076_lazy_tabs.js
@@ -100,7 +100,7 @@ add_task(async function test() {
     !gBrowser.browsers[1].isConnected,
     "The browser that we're attempting to insert is indeed lazy"
   );
-  gBrowser._insertBrowser(gBrowser.tabs[1]);
+  gBrowser.insertBrowser(gBrowser.tabs[1]);
   is(countNonLazyTabs(), 2, "Window now has 2 non-lazy tabs");
 
   // Check if any lazy tabs got inserted when window closes.
@@ -122,7 +122,7 @@ add_task(async function test() {
           !newWindow.gBrowser.browsers[1].isConnected,
           "The browser that we're attempting to insert is indeed lazy"
         );
-        newWindow.gBrowser._insertBrowser(newWindow.gBrowser.tabs[1]);
+        newWindow.gBrowser.insertBrowser(newWindow.gBrowser.tabs[1]);
         is(
           countNonLazyTabs(newWindow),
           1,
diff --git a/src/zen/tests/mochitests/sessionstore/browser_duplicate_history.js b/src/zen/tests/mochitests/sessionstore/browser_duplicate_history.js
index 6bb251139..e12e3ac45 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_duplicate_history.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_duplicate_history.js
@@ -1,6 +1,8 @@
 ChromeUtils.defineESModuleGetters(this, {
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
-  TabStateCache: "resource:///modules/sessionstore/TabStateCache.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
+  TabStateCache:
+    "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs",
 });
 
 add_task(async function () {
diff --git a/src/zen/tests/mochitests/sessionstore/browser_duplicate_tab_in_new_window.js b/src/zen/tests/mochitests/sessionstore/browser_duplicate_tab_in_new_window.js
index d3baf1cd4..2728723ae 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_duplicate_tab_in_new_window.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_duplicate_tab_in_new_window.js
@@ -1,5 +1,6 @@
 ChromeUtils.defineESModuleGetters(this, {
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
 });
 
 add_task(async function () {
diff --git a/src/zen/tests/mochitests/sessionstore/browser_firefoxView_selected_restore.js b/src/zen/tests/mochitests/sessionstore/browser_firefoxView_selected_restore.js
index 2538e444b..19e295593 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_firefoxView_selected_restore.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_firefoxView_selected_restore.js
@@ -2,7 +2,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
 const { _LastSession } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionStore.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
 );
 const { sinon } = ChromeUtils.importESModule(
   "resource://testing-common/Sinon.sys.mjs"
diff --git a/src/zen/tests/mochitests/sessionstore/browser_oldformat.toml b/src/zen/tests/mochitests/sessionstore/browser_oldformat.toml
index 348a0c004..4a063cb28 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_oldformat.toml
+++ b/src/zen/tests/mochitests/sessionstore/browser_oldformat.toml
@@ -153,7 +153,7 @@ skip-if = [
 
 ["browser_477657.js"]
 skip-if = [
-  "os == 'linux' && os_version == '22.04' && arch == 'x86_64' && opt && nova", # Bug 2057857
+  "os == 'linux' && os_version == '22.04' && arch == 'x86_64'", # Bug 2057857
   "os == 'linux' && os_version == '24.04' && arch == 'x86_64' && display == 'x11'", # Bug 1610668
 ]
 
@@ -184,7 +184,7 @@ skip-if = [
 
 ["browser_524745.js"]
 skip-if = [
-  "os == 'linux' && os_version == '22.04' && arch == 'x86_64' && debug && nova", # Bug 2057858
+  "os == 'linux' && os_version == '22.04' && arch == 'x86_64'", # Bug 2057858
 ]
 
 ["browser_528776.js"]
diff --git a/src/zen/tests/mochitests/sessionstore/browser_restoreLastActionCorrectOrder.js b/src/zen/tests/mochitests/sessionstore/browser_restoreLastActionCorrectOrder.js
index bd660a4bd..c65c595a2 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_restoreLastActionCorrectOrder.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_restoreLastActionCorrectOrder.js
@@ -1,12 +1,12 @@
 "use strict";
 
 const { _LastSession, _lastClosedActions } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionStore.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
 );
 
 /**
  * Tests that the _lastClosedAction list is truncated correctly
- * by removing oldest actions in SessionStore._addClosedAction
+ * by removing oldest actions in SessionStore's #addClosedAction
  */
 add_task(async function test_undo_last_action_correct_order() {
   SpecialPowers.pushPrefEnv({
diff --git a/src/zen/tests/mochitests/sessionstore/browser_restoreLastClosedTabOrWindowOrSession.js b/src/zen/tests/mochitests/sessionstore/browser_restoreLastClosedTabOrWindowOrSession.js
index f7e2f38e4..467e4b6bd 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_restoreLastClosedTabOrWindowOrSession.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_restoreLastClosedTabOrWindowOrSession.js
@@ -4,7 +4,7 @@
 "use strict";
 
 const { _LastSession, _lastClosedActions } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionStore.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
 );
 
 async function testLastClosedActionsEntries() {
diff --git a/src/zen/tests/mochitests/sessionstore/browser_restore_respects_pending_minimize.js b/src/zen/tests/mochitests/sessionstore/browser_restore_respects_pending_minimize.js
new file mode 100644
index 000000000..76a450eb5
--- /dev/null
+++ b/src/zen/tests/mochitests/sessionstore/browser_restore_respects_pending_minimize.js
@@ -0,0 +1,135 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const { sinon } = ChromeUtils.importESModule(
+  "resource://testing-common/Sinon.sys.mjs"
+);
+
+function holdNextZeroTimeout(win) {
+  const realSetTimeout = win.setTimeout.bind(win);
+  let callback;
+  let callbackArgs;
+  let holding = true;
+
+  const stub = sinon.stub(win, "setTimeout").callsFake((fn, delay, ...args) => {
+    if (!callback && delay === 0) {
+      callback = fn;
+      callbackArgs = args;
+      return 1;
+    }
+    return realSetTimeout(fn, delay, ...args);
+  });
+
+  return {
+    stopHolding() {
+      if (!holding) {
+        return;
+      }
+      holding = false;
+      stub.restore();
+      Assert.ok(callback, "captured the window feature restore timer");
+    },
+
+    run() {
+      callback(...callbackArgs);
+    },
+  };
+}
+
+async function setSizeMode(win, method) {
+  const changed = BrowserTestUtils.waitForEvent(win, "sizemodechange");
+  win[method]();
+  await changed;
+}
+
+function getWindowState(win, sizemode = "normal") {
+  return {
+    windows: [
+      {
+        tabs: [{ entries: [] }],
+        width: Math.max(200, win.outerWidth - 20),
+        height: Math.max(200, win.outerHeight - 20),
+        screenX: win.screenX,
+        screenY: win.screenY,
+        sizemode,
+      },
+    ],
+  };
+}
+
+add_task(async function test_minimize_while_restore_is_pending_wins() {
+  const win = await BrowserTestUtils.openNewBrowserWindow();
+  let heldTimer;
+
+  registerCleanupFunction(async () => {
+    if (!win.closed) {
+      heldTimer?.stopHolding();
+      await BrowserTestUtils.closeWindow(win);
+    }
+  });
+
+  if (win.windowState != win.STATE_NORMAL) {
+    await setSizeMode(win, "restore");
+  }
+
+  heldTimer = holdNextZeroTimeout(win);
+  const restoring = promiseWindowRestoring(win);
+  const restored = promiseWindowRestored(win);
+  ss.setWindowState(win, JSON.stringify(getWindowState(win)), true);
+  await restoring;
+  heldTimer.stopHolding();
+
+  if (win.windowState != win.STATE_MINIMIZED) {
+    await setSizeMode(win, "minimize");
+  }
+
+  heldTimer.run();
+  await restored;
+
+  Assert.equal(
+    win.windowState,
+    win.STATE_MINIMIZED,
+    "the newer minimized state is preserved"
+  );
+
+  if (win.windowState == win.STATE_MINIMIZED) {
+    await setSizeMode(win, "restore");
+  }
+  await BrowserTestUtils.closeWindow(win);
+});
+
+add_task(async function test_initial_minimized_state_is_still_restored() {
+  const win = await BrowserTestUtils.openNewBrowserWindow();
+  let heldTimer;
+
+  registerCleanupFunction(async () => {
+    if (!win.closed) {
+      heldTimer?.stopHolding();
+      await BrowserTestUtils.closeWindow(win);
+    }
+  });
+
+  if (win.windowState != win.STATE_MINIMIZED) {
+    await setSizeMode(win, "minimize");
+  }
+
+  heldTimer = holdNextZeroTimeout(win);
+  const restoring = promiseWindowRestoring(win);
+  const restored = promiseWindowRestored(win);
+  ss.setWindowState(win, JSON.stringify(getWindowState(win)), true);
+  await restoring;
+  heldTimer.stopHolding();
+
+  const sizeModeChanged = BrowserTestUtils.waitForEvent(win, "sizemodechange");
+  heldTimer.run();
+  await Promise.all([restored, sizeModeChanged]);
+
+  Assert.equal(
+    win.windowState,
+    win.STATE_NORMAL,
+    "still applies saved state when the window was already minimized"
+  );
+
+  await BrowserTestUtils.closeWindow(win);
+});
diff --git a/src/zen/tests/mochitests/sessionstore/browser_restored_window_features.js b/src/zen/tests/mochitests/sessionstore/browser_restored_window_features.js
index 64aca7910..a9f5e909d 100644
--- a/src/zen/tests/mochitests/sessionstore/browser_restored_window_features.js
+++ b/src/zen/tests/mochitests/sessionstore/browser_restored_window_features.js
@@ -3,13 +3,7 @@
 
 "use strict";
 
-const BARPROP_NAMES = [
-  "locationbar",
-  "menubar",
-  "personalbar",
-  "scrollbars",
-  "toolbar",
-];
+const BARPROP_NAMES = ["locationbar", "menubar", "personalbar", "toolbar"];
 
 function testFeatures(win, test) {
   for (let name of BARPROP_NAMES) {
@@ -43,14 +37,13 @@ add_task(async function testRestoredWindowFeatures() {
     locationbar: true,
     menubar: true,
     personalbar: true,
-    scrollbars: true,
     toolbar: true,
   };
   const TESTS = [
     {
       url: "http://example.com/browser/" + DUMMY_PAGE,
       features: "menubar=0,resizable",
-      barprops: { scrollbars: true },
+      barprops: { locationbar: true },
       chromeFlags: Ci.nsIWebBrowserChrome.CHROME_WINDOW_RESIZE,
       unsetFlags: Ci.nsIWebBrowserChrome.CHROME_OPENAS_DIALOG,
     },
@@ -58,14 +51,14 @@ add_task(async function testRestoredWindowFeatures() {
       url: "data:,", // title should be empty
       checkContentTitleEmpty: true,
       features: "location,resizable",
-      barprops: { locationbar: true, scrollbars: true },
+      barprops: { locationbar: true },
       chromeFlags: Ci.nsIWebBrowserChrome.CHROME_WINDOW_RESIZE,
       unsetFlags: Ci.nsIWebBrowserChrome.CHROME_OPENAS_DIALOG,
     },
     {
       url: "http://example.com/browser/" + DUMMY_PAGE,
       features: "dialog,resizable",
-      barprops: { scrollbars: true },
+      barprops: { locationbar: true },
       chromeFlags:
         Ci.nsIWebBrowserChrome.CHROME_OPENAS_DIALOG |
         Ci.nsIWebBrowserChrome.CHROME_WINDOW_RESIZE,
diff --git a/src/zen/tests/mochitests/sessionstore/head.js b/src/zen/tests/mochitests/sessionstore/head.js
index 78f777a42..75c112330 100644
--- a/src/zen/tests/mochitests/sessionstore/head.js
+++ b/src/zen/tests/mochitests/sessionstore/head.js
@@ -18,23 +18,23 @@ const HTTPSROOT = ROOT.replace(
 );
 
 const { SessionSaver } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionSaver.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionSaver.sys.mjs"
 );
 const { SessionFile } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionFile.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
 );
 const { TabState } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/TabState.sys.mjs"
+  "moz-src:///browser/components/sessionstore/TabState.sys.mjs"
 );
 const { TabStateFlusher } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+  "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
 );
 const { SessionStoreTestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/SessionStoreTestUtils.sys.mjs"
 );
 
 const { PageWireframes } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/PageWireframes.sys.mjs"
+  "moz-src:///browser/components/sessionstore/PageWireframes.sys.mjs"
 );
 
 const ss = SessionStore;
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/manifest.toml b/src/zen/tests/mochitests/sessionstore/marionette/manifest.toml
index e66c364ca..8275c755d 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/manifest.toml
+++ b/src/zen/tests/mochitests/sessionstore/marionette/manifest.toml
@@ -48,6 +48,10 @@ skip-if = [
   "os == 'win' && os_version == '11.26200' && arch == 'x86_64'", # Bug 1727691
 ]
 
+["test_shutdown_flush_timeout.py"]
+
+["test_splitview_hidden.py"]
+
 ["test_splitview_restore.py"]
 
 ["test_tabgroups_restore.py"]
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/session_store_test_case.py b/src/zen/tests/mochitests/sessionstore/marionette/session_store_test_case.py
index 8c76be10e..c6566ada0 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/session_store_test_case.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/session_store_test_case.py
@@ -156,7 +156,7 @@ class SessionStoreTestCase(WindowManagerMixin, MarionetteTestCase):
                         null,
                         AppConstants.BROWSER_CHROME_URL,
                         "_blank",
-                        "chrome,dialog=no,titlebar,close,toolbar,location,personalbar=no,status,menubar=no,resizable,minimizable,scrollbars",
+                        "chrome,dialog=no,titlebar,close,toolbar,location,personalbar=no,status,menubar=no,resizable,minimizable",
                         args
                     );
                     await new Promise(resolve => {
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_new_tab_on_restore.py b/src/zen/tests/mochitests/sessionstore/marionette/test_new_tab_on_restore.py
index 81543b746..50c7a8628 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_new_tab_on_restore.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_new_tab_on_restore.py
@@ -246,7 +246,7 @@ class TestNewTabOnRestoreNotSettingBased(SessionStoreTestCase):
         self.marionette.execute_script(
             """
             const { SessionStore } = ChromeUtils.importESModule(
-                "resource:///modules/sessionstore/SessionStore.sys.mjs"
+                "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
             );
             SessionStore.restoreLastSession();
             """
@@ -294,10 +294,10 @@ class TestNewTabOnRestoreAfterCrash(SessionStoreTestCase):
             let [resolve] = arguments;
             Services.prefs.savePrefFile(Services.dirsvc.get("PrefF", Ci.nsIFile));
             const { TabStateFlusher } = ChromeUtils.importESModule(
-                "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+                "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
             );
             const { SessionSaver } = ChromeUtils.importESModule(
-                "resource:///modules/sessionstore/SessionSaver.sys.mjs"
+                "moz-src:///browser/components/sessionstore/SessionSaver.sys.mjs"
             );
             (async () => {
                 for (let win of Services.wm.getEnumerator("navigator:browser")) {
@@ -318,7 +318,7 @@ class TestNewTabOnRestoreAfterCrash(SessionStoreTestCase):
             """
             let [resolve] = arguments;
             const { SessionStore } = ChromeUtils.importESModule(
-                "resource:///modules/sessionstore/SessionStore.sys.mjs"
+                "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
             );
             SessionStore.promiseAllWindowsRestored.then(resolve);
             """
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_persist_closed_tabs_restore_manually.py b/src/zen/tests/mochitests/sessionstore/marionette/test_persist_closed_tabs_restore_manually.py
index 1a58a92da..c917630a0 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_persist_closed_tabs_restore_manually.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_persist_closed_tabs_restore_manually.py
@@ -58,7 +58,7 @@ class TestSessionRestoreClosedTabs(SessionStoreTestCase):
             let resolve = arguments[0];
             let tab = gBrowser.tabs[1];
             gBrowser.removeTab(tab);
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flush(tab).then(resolve);
             """
         )
@@ -70,7 +70,7 @@ class TestSessionRestoreClosedTabs(SessionStoreTestCase):
         self.assertEqual(
             self.marionette.execute_script(
                 """
-            let { SessionStore } = ChromeUtils.importESModule("resource:///modules/sessionstore/SessionStore.sys.mjs");
+            let { SessionStore } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/SessionStore.sys.mjs");
             let state = JSON.parse(SessionStore.getBrowserState());
             return state.windows[0]._closedTabs.length;
             """
@@ -82,7 +82,7 @@ class TestSessionRestoreClosedTabs(SessionStoreTestCase):
         self.assertEqual(
             self.marionette.execute_script(
                 """
-            let { SessionStore } = ChromeUtils.importESModule("resource:///modules/sessionstore/SessionStore.sys.mjs");
+            let { SessionStore } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/SessionStore.sys.mjs");
             let state = JSON.parse(SessionStore.getBrowserState());
             return state.windows[0]._closedTabs[0].removeAfterRestore;
             """
@@ -130,7 +130,7 @@ class TestSessionRestoreClosedTabs(SessionStoreTestCase):
             let resolve = arguments[0];
             let tab = gBrowser.tabs[1];
             gBrowser.removeTab(tab);
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flush(tab).then(resolve);
             """
         )
@@ -143,7 +143,7 @@ class TestSessionRestoreClosedTabs(SessionStoreTestCase):
                 """
                 const lazy = {};
                 ChromeUtils.defineESModuleGetters(lazy, {
-                    SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+                    SessionStore: "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
                 });
                 function observeClosedTabsChange() {
                     return new Promise(resolve => {
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_aiwindow.py b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_aiwindow.py
index b899a392d..8d1301018 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_aiwindow.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_aiwindow.py
@@ -66,7 +66,7 @@ class AIWindowTestMixin:
             """
             const lazy = {};
             ChromeUtils.defineESModuleGetters(lazy, {
-                SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+                SessionStore: "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
             });
             function observeClosedObjectsChange() {
                 return new Promise(resolve => {
@@ -117,7 +117,7 @@ class SmartWindowDefaultMixin(AIWindowTestMixin):
         return self.marionette.execute_script(
             """
             const { SessionStore } = ChromeUtils.importESModule(
-                "resource:///modules/sessionstore/SessionStore.sys.mjs"
+                "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
             );
             return SessionStore.canRestoreLastSession;
             """
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually.py b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually.py
index 0f3291f2e..e2db0f5a0 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually.py
@@ -95,7 +95,7 @@ class TestSessionRestoreManually(SessionStoreTestCase):
             """
             const lazy = {};
             ChromeUtils.defineESModuleGetters(lazy, {
-                SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+                SessionStore: "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
             });
             function observeClosedObjectsChange() {
                 return new Promise(resolve => {
@@ -129,7 +129,7 @@ class TestSessionRestoreManually(SessionStoreTestCase):
                 """
                 const lazy = {};
                 ChromeUtils.defineESModuleGetters(lazy, {
-                    SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+                    SessionStore: "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
                 });
                 let state = SessionStore.getCurrentState()
                 return state.windows[1]["height"]
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_pinned_tabs.py b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_pinned_tabs.py
index 5e92dce2b..8f396dae0 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_pinned_tabs.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_pinned_tabs.py
@@ -42,7 +42,7 @@ class TestSessionRestoreWithPinnedTabs(SessionStoreTestCase):
             """
             let resolve = arguments[0];
             gBrowser.pinTab(gBrowser.tabs[0]);
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flush(gBrowser.tabs[0]).then(resolve);
         """
         )
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_tab_groups.py b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_tab_groups.py
index b3f727822..af07ed849 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_tab_groups.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_manually_with_tab_groups.py
@@ -47,7 +47,7 @@ class TestSessionRestoreWithTabGroups(SessionStoreTestCase):
             let closedGroup = gBrowser.addTabGroup([gBrowser.tabs[1]], { id:"group-closed", label: "closed" });
             gBrowser.removeTabGroup(closedGroup);
 
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
         """
         )
@@ -144,7 +144,7 @@ class TestSessionRestoreWithTabGroups(SessionStoreTestCase):
         self.marionette.execute_script(
             """
             let group = gBrowser.addTabGroup([...gBrowser.tabs], { id: "group-to-save", label: "to-save" });
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(() => {
                 group.saveAndClose();
             });
@@ -181,7 +181,7 @@ class TestSessionRestoreWithTabGroups(SessionStoreTestCase):
             gBrowser.addTabGroup([gBrowser.tabs[3], gBrowser.tabs[4]], { id: "save-through-restore-1", label: "open-1" });
             gBrowser.addTabGroup([gBrowser.tabs[1], gBrowser.tabs[2]], { id: "save-through-restore-2", label: "open-2" });
 
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
         """
         )
@@ -252,7 +252,7 @@ class TestSessionRestoreWithTabGroups(SessionStoreTestCase):
             gBrowser.addTabGroup([gBrowser.tabs[3], gBrowser.tabs[4]], { id: "not-saved-after-restore-1", label: "open-1" });
             gBrowser.addTabGroup([gBrowser.tabs[1], gBrowser.tabs[2]], { id: "not-saved-after-restore-2", label: "open-2" });
 
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
             """
         )
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar.py b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar.py
index fcccf7c13..15d410350 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar.py
@@ -97,7 +97,7 @@ class TestSessionRestore(SessionStoreTestCase):
                 """
                 const lazy = {};
                 ChromeUtils.defineESModuleGetters(lazy, {
-                    SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+                    SessionStore: "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
                 });
                 let state = SessionStore.getCurrentState();
                 return state.windows[0].sidebar.command;
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar_automatic.py b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar_automatic.py
index 19c64844c..f57bef8f1 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar_automatic.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_restore_sidebar_automatic.py
@@ -95,7 +95,7 @@ class TestSessionRestore(SessionStoreTestCase):
                 """
                 const lazy = {};
                 ChromeUtils.defineESModuleGetters(lazy, {
-                    SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+                    SessionStore: "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
                 });
                 let state = SessionStore.getCurrentState();
                 return state.windows[0].sidebar.command;
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_shutdown_flush_timeout.py b/src/zen/tests/mochitests/sessionstore/marionette/test_shutdown_flush_timeout.py
new file mode 100644
index 000000000..714a04fdd
--- /dev/null
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_shutdown_flush_timeout.py
@@ -0,0 +1,92 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import time
+from urllib.parse import quote
+
+from marionette_harness import MarionetteTestCase, WindowManagerMixin
+
+
+def inline(doc):
+    return f"data:text/html;charset=utf-8,{quote(doc)}"
+
+
+# The page blocks its content process for this long, which has to outlast the
+# loose timer's first beat, one second into the shutdown flush.
+CONTENT_BUSY_MS = 10000
+
+# Give the navigation time to settle before the block starts, so that it is the
+# shutdown flush that gets stuck rather than the test's own setup.
+CONTENT_BUSY_DELAY_MS = 500
+
+TIMED_OUT_PATTERN = r"looseTimer of \d+ timed out"
+
+
+class TestShutdownFlushTimeout(WindowManagerMixin, MarionetteTestCase):
+    """Shutdown races the window flushes against a loose timer, so that an
+    unresponsive content process cannot stall quitting. This covers the timer
+    winning that race, which only happens when its callback can reach the
+    logger."""
+
+    def setUp(self):
+        super().setUp()
+        self.marionette.enforce_gecko_prefs({
+            "browser.sessionstore.loglevel": "Debug",
+            "browser.sessionstore.log.appender.file.logOnSuccess": True,
+            # The timer waits DELAY_CRASH_MS - 10000, so this brings it forward
+            # to its first beat.
+            "toolkit.asyncshutdown.crash_timeout": 10000,
+        })
+
+    def tearDown(self):
+        try:
+            # Create a fresh profile for subsequent tests.
+            self.marionette.restart(in_app=False, clean=True)
+        finally:
+            super().tearDown()
+
+    def getLogContents(self):
+        profilePath = self.marionette.instance.profile.profile
+        assert profilePath is not None
+        dirPath = os.path.join(profilePath, "sessionstore-logs")
+        if not os.path.isdir(dirPath):
+            return ""
+        contents = []
+        for entry in os.scandir(dirPath):
+            if entry.is_file():
+                with open(entry.path) as f:
+                    contents.append(f.read())
+        return "\n".join(contents)
+
+    def quitFromParent(self):
+        with self.marionette.using_context("chrome"):
+            self.marionette.execute_script(
+                "Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit);"
+            )
+
+    def test_flush_timeout_is_logged(self):
+        # The page blocks its own content process shortly after loading, so the
+        # parent cannot collect its tab state and the timer wins the race.
+        with self.marionette.using_context("content"):
+            self.marionette.navigate(
+                inline(
+                    "<script>"
+                    f"setTimeout(() => {{ const end = Date.now() + {CONTENT_BUSY_MS};"
+                    " while (Date.now() < end) {} }, "
+                    f"{CONTENT_BUSY_DELAY_MS});"
+                    "</script>"
+                )
+            )
+        time.sleep((CONTENT_BUSY_DELAY_MS + 500) / 1000)
+
+        self.marionette.quit(callback=self.quitFromParent)
+
+        self.assertRegex(
+            self.getLogContents(),
+            TIMED_OUT_PATTERN,
+            "The loose timer resolved the shutdown flush race",
+        )
+
+        self.marionette.start_session()
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_hidden.py b/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_hidden.py
new file mode 100644
index 000000000..f09e93ea5
--- /dev/null
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_hidden.py
@@ -0,0 +1,201 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# add this directory to the path
+import os
+import sys
+from urllib.parse import quote
+
+sys.path.append(os.path.dirname(__file__))
+
+from session_store_test_case import SessionStoreTestCase
+
+
+def inline(doc):
+    return f"data:text/html;charset=utf-8,{quote(doc)}"
+
+
+# Each list element represents a window of tabs loaded at
+# some testing URL
+DEFAULT_WINDOWS = set([
+    # Window 1. Note the comma after the inline call -
+    # this is Python's way of declaring a 1 item tuple.
+    (
+        inline("""<div">Lorem</div>"""),
+        inline("""<div">Ipsum</div>"""),
+        inline("""<div">Dolor</div>"""),
+        inline("""<div">sit</div>"""),
+        inline("""<div">amet</div>"""),
+    ),
+])
+
+RETURN_HIDDEN_TAB_COUNT = """
+return gBrowser.tabs.reduce((count, t) => count + (t.hidden ? 1 : 0), 0)
+"""
+
+
+class TestHiddenTabsRestoreWithSplitView(SessionStoreTestCase):
+    def setUp(self):
+        super().setUp(
+            startup_page=3,
+            include_private=False,
+            restore_on_demand=True,
+            test_windows=DEFAULT_WINDOWS,
+        )
+        self.marionette.set_context("chrome")
+
+    def test_splitview_no_hidden_tabs(self):
+        self.wait_for_windows(
+            self.all_windows, "Not all requested windows have been opened"
+        )
+
+        self.marionette.execute_async_script(
+            """
+            let resolve = arguments[0];
+            gBrowser.addTabSplitView([gBrowser.tabs[0], gBrowser.tabs[1]], {
+            insertBefore: gBrowser.tabs[0],
+            });
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
+            TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
+            """
+        )
+
+        self.assertEqual(
+            self.marionette.execute_script(RETURN_HIDDEN_TAB_COUNT),
+            0,
+            "No tabs are hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.splitViews.every(t => !t.hasAttribute('hidden'))"
+            ),
+            "No split views are hidden",
+        )
+
+        self.marionette.quit()
+        self.marionette.start_session()
+        self.marionette.set_context("chrome")
+
+        self.assertEqual(
+            self.marionette.execute_script(RETURN_HIDDEN_TAB_COUNT),
+            0,
+            "No tabs are restored hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.splitViews.every(t => !t.hasAttribute('hidden'))"
+            ),
+            "No restored split views are hidden",
+        )
+
+    def test_splitview_both_hidden(self):
+        """
+        Hiding one tab in a split view should hide both of the tabs and the
+        split view container. They should be restored in the same state.
+        """
+        self.wait_for_windows(
+            self.all_windows, "Not all requested windows have been opened"
+        )
+
+        self.marionette.execute_async_script(
+            """
+            let resolve = arguments[0];
+            gBrowser.addTabSplitView([gBrowser.tabs[0], gBrowser.tabs[1]], {
+            insertBefore: gBrowser.tabs[0],
+            });
+            gBrowser.hideTab(gBrowser.tabs[0]);
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
+            TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
+            """
+        )
+
+        self.assertEqual(
+            self.marionette.execute_script(RETURN_HIDDEN_TAB_COUNT),
+            2,
+            "Two tabs are hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.tabs[0].hidden && gBrowser.tabs[1].hidden"
+            ),
+            "The right tabs are hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.splitViews[0].hasAttribute('hidden')"
+            ),
+            "The split view is hidden because both tabs in it are hidden",
+        )
+
+        self.marionette.quit()
+        self.marionette.start_session()
+        self.marionette.set_context("chrome")
+
+        self.assertEqual(
+            self.marionette.execute_script(RETURN_HIDDEN_TAB_COUNT),
+            2,
+            "Two tabs are restored hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.tabs[0].hidden && gBrowser.tabs[1].hidden"
+            ),
+            "The right tabs are restored hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.splitViews[0].hasAttribute('hidden')"
+            ),
+            "The split view is restored hidden",
+        )
+
+    def test_splitview_in_collapsed_group_is_not_hidden(self):
+        """
+        Bug 2063789: ensure split views that are invisible (e.g. in a collapsed
+        group) but not actually hidden are restored not hidden.
+        """
+        self.wait_for_windows(
+            self.all_windows, "Not all requested windows have been opened"
+        )
+
+        self.marionette.execute_async_script(
+            """
+            let resolve = arguments[0];
+            let splitview = gBrowser.addTabSplitView([gBrowser.tabs[0], gBrowser.tabs[1]], {
+            insertBefore: gBrowser.tabs[0],
+            });
+            let group = gBrowser.addTabGroup([splitview, gBrowser.tabs[2]], { insertBefore: splitview });
+            group.collapsed = true;
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
+            TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
+            """
+        )
+
+        self.assertEqual(
+            self.marionette.execute_script(RETURN_HIDDEN_TAB_COUNT),
+            0,
+            "No tabs are hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.splitViews.every(t => !t.hasAttribute('hidden'))"
+            ),
+            "No split views are hidden",
+        )
+
+        self.marionette.quit()
+        self.marionette.start_session()
+        self.marionette.set_context("chrome")
+
+        self.assertEqual(
+            self.marionette.execute_script(RETURN_HIDDEN_TAB_COUNT),
+            0,
+            "No tabs are restored hidden",
+        )
+        self.assertTrue(
+            self.marionette.execute_script(
+                "return gBrowser.splitViews.every(t => !t.hasAttribute('hidden'))"
+            ),
+            "No restored split views are hidden",
+        )
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_restore.py b/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_restore.py
index 81239d34d..3cc3de41b 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_restore.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_splitview_restore.py
@@ -53,7 +53,7 @@ class TestAutoRestoreWithSplitView(SessionStoreTestCase):
             gBrowser.addTabSplitView([gBrowser.tabs[0], gBrowser.tabs[1]], {
             insertBefore: gBrowser.tabs[0],
             });
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
             """
         )
@@ -98,7 +98,7 @@ class TestAutoRestoreWithSplitView(SessionStoreTestCase):
             insertBefore: gBrowser.tabs[2],
             });
             gBrowser.selectedTab = gBrowser.tabs[2];
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
             """
         )
@@ -150,7 +150,7 @@ class TestAutoRestoreWithSplitView(SessionStoreTestCase):
             gBrowser.addTabSplitView([gBrowser.tabs[0], gBrowser.tabs[1]], {
                 insertBefore: gBrowser.tabs[0],
             });
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
             """
         )
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_tabgroups_restore.py b/src/zen/tests/mochitests/sessionstore/marionette/test_tabgroups_restore.py
index c4c13ea6a..bab6b0671 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_tabgroups_restore.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_tabgroups_restore.py
@@ -45,7 +45,7 @@ class TestAutoRestoreWithTabGroups(SessionStoreTestCase):
             """
             let resolve = arguments[0];
             let group = gBrowser.addTabGroup([gBrowser.tabs[0]], { id: "test-group", label: "test-group" });
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
             """
         )
@@ -121,7 +121,7 @@ class TestAutoRestoreWithTabGroups(SessionStoreTestCase):
             """
             let resolve = arguments[0];
             let group = gBrowser.addTabGroup([gBrowser.tabs[0]], { id: "test-group", label: "test-group" });
-            let { TabStateFlusher } = ChromeUtils.importESModule("resource:///modules/sessionstore/TabStateFlusher.sys.mjs");
+            let { TabStateFlusher } = ChromeUtils.importESModule("moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs");
             TabStateFlusher.flushWindow(gBrowser.documentGlobal).then(resolve);
             """
         )
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_tabnotes_canonicalurl_restore.py b/src/zen/tests/mochitests/sessionstore/marionette/test_tabnotes_canonicalurl_restore.py
index bfa41cc4d..cb937a75a 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_tabnotes_canonicalurl_restore.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_tabnotes_canonicalurl_restore.py
@@ -73,7 +73,7 @@ class TestCanonicalUrlRestore(SessionStoreTestCase):
                 await TabNotes.set(pendingTab, "Note for pending tab");
 
                 let {{ TabStateFlusher }} = ChromeUtils.importESModule(
-                    "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+                    "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
                 );
                 await TabStateFlusher.flushWindow(gBrowser.documentGlobal);
             }})().then(resolve);
@@ -151,7 +151,7 @@ class TestCanonicalUrlRestore(SessionStoreTestCase):
                 tab.canonicalUrl = "{CANONICAL_URL}";
 
                 let {{ TabStateFlusher }} = ChromeUtils.importESModule(
-                    "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+                    "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
                 );
                 await TabStateFlusher.flushWindow(gBrowser.documentGlobal);
             }})().then(resolve);
diff --git a/src/zen/tests/mochitests/sessionstore/marionette/test_taskbartab_sessionstate.py b/src/zen/tests/mochitests/sessionstore/marionette/test_taskbartab_sessionstate.py
index 7f75f27df..1254fbebf 100644
--- a/src/zen/tests/mochitests/sessionstore/marionette/test_taskbartab_sessionstate.py
+++ b/src/zen/tests/mochitests/sessionstore/marionette/test_taskbartab_sessionstate.py
@@ -64,7 +64,7 @@ class TestTaskbarTabSessionState(SessionStoreTestCase):
             self.marionette.execute_script(
                 """
                 const { _LastSession } = ChromeUtils.importESModule(
-                    "resource:///modules/sessionstore/SessionStore.sys.mjs"
+                    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
                     );
                 return _LastSession.getState().windows.length
             """
@@ -77,7 +77,7 @@ class TestTaskbarTabSessionState(SessionStoreTestCase):
             self.marionette.execute_script(
                 """
                 const { _LastSession } = ChromeUtils.importESModule(
-                    "resource:///modules/sessionstore/SessionStore.sys.mjs"
+                    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs"
                     );
                 return _LastSession.getState().windows[0].tabs.length
             """
diff --git a/src/zen/tests/mochitests/sessionstore/unit/head.js b/src/zen/tests/mochitests/sessionstore/unit/head.js
index 03f7e8239..52ffae279 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/head.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/head.js
@@ -1,6 +1,8 @@
 ChromeUtils.defineESModuleGetters(this, {
-  SessionStartup: "resource:///modules/sessionstore/SessionStartup.sys.mjs",
-  SessionStore: "resource:///modules/sessionstore/SessionStore.sys.mjs",
+  SessionStartup:
+    "moz-src:///browser/components/sessionstore/SessionStartup.sys.mjs",
+  SessionStore:
+    "moz-src:///browser/components/sessionstore/SessionStore.sys.mjs",
 });
 
 // Call a function once initialization of SessionStartup is complete
diff --git a/src/zen/tests/mochitests/sessionstore/unit/test_backup_once.js b/src/zen/tests/mochitests/sessionstore/unit/test_backup_once.js
index db566491d..36367cdaa 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/test_backup_once.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/test_backup_once.js
@@ -4,13 +4,13 @@
 "use strict";
 
 const { SessionWriter } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionWriter.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionWriter.sys.mjs"
 );
 
 // Make sure that we have a profile before initializing SessionFile.
 const profd = do_get_profile();
 const { SessionFile } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionFile.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
 );
 const Paths = SessionFile.Paths;
 
diff --git a/src/zen/tests/mochitests/sessionstore/unit/test_final_write_cleanup.js b/src/zen/tests/mochitests/sessionstore/unit/test_final_write_cleanup.js
index b3fbd6b20..c33934d25 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/test_final_write_cleanup.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/test_final_write_cleanup.js
@@ -8,7 +8,7 @@
  */
 
 const { SessionWriter } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionWriter.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionWriter.sys.mjs"
 );
 
 // Make sure that we have a profile before initializing SessionFile.
@@ -16,7 +16,7 @@ do_get_profile();
 const {
   SessionFile: { Paths },
 } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionFile.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
 );
 
 const MAX_ENTRIES = 9;
diff --git a/src/zen/tests/mochitests/sessionstore/unit/test_histogram_corrupt_files.js b/src/zen/tests/mochitests/sessionstore/unit/test_histogram_corrupt_files.js
index 2c469ed3b..10943480e 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/test_histogram_corrupt_files.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/test_histogram_corrupt_files.js
@@ -15,7 +15,7 @@ const HistogramId = "FX_SESSION_RESTORE_ALL_FILES_CORRUPT";
 // Prepare the session file.
 do_get_profile();
 const { SessionFile } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionFile.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
 );
 
 /**
diff --git a/src/zen/tests/mochitests/sessionstore/unit/test_migration_lz4compression.js b/src/zen/tests/mochitests/sessionstore/unit/test_migration_lz4compression.js
index 4d9b700d8..bf2f6bbf2 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/test_migration_lz4compression.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/test_migration_lz4compression.js
@@ -1,13 +1,13 @@
 "use strict";
 
 const { SessionWriter } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionWriter.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionWriter.sys.mjs"
 );
 
 // Make sure that we have a profile before initializing SessionFile.
 const profd = do_get_profile();
 const { SessionFile } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionFile.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
 );
 const Paths = SessionFile.Paths;
 
diff --git a/src/zen/tests/mochitests/sessionstore/unit/test_startup_invalid_session.js b/src/zen/tests/mochitests/sessionstore/unit/test_startup_invalid_session.js
index 50960b1d4..72d457df6 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/test_startup_invalid_session.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/test_startup_invalid_session.js
@@ -4,7 +4,7 @@
 function run_test() {
   let profd = do_get_profile();
   var SessionFile = ChromeUtils.importESModule(
-    "resource:///modules/sessionstore/SessionFile.sys.mjs"
+    "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
   ).SessionFile;
 
   let sourceSession = do_get_file("data/sessionstore_invalid.js");
diff --git a/src/zen/tests/mochitests/sessionstore/unit/test_startup_session_async.js b/src/zen/tests/mochitests/sessionstore/unit/test_startup_session_async.js
index a61c9fe42..2365fd216 100644
--- a/src/zen/tests/mochitests/sessionstore/unit/test_startup_session_async.js
+++ b/src/zen/tests/mochitests/sessionstore/unit/test_startup_session_async.js
@@ -9,7 +9,7 @@
 function run_test() {
   let profd = do_get_profile();
   var SessionFile = ChromeUtils.importESModule(
-    "resource:///modules/sessionstore/SessionFile.sys.mjs"
+    "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
   ).SessionFile;
 
   let sourceSession = do_get_file("data/sessionstore_valid.js");
diff --git a/src/zen/tests/mochitests/sync/test_addon_utils.js b/src/zen/tests/mochitests/sync/test_addon_utils.js
index e9e49fb9e..eaff6d757 100644
--- a/src/zen/tests/mochitests/sync/test_addon_utils.js
+++ b/src/zen/tests/mochitests/sync/test_addon_utils.js
@@ -6,6 +6,12 @@
 const { AddonUtils } = ChromeUtils.importESModule(
   "resource://services-sync/addonutils.sys.mjs"
 );
+const { EnterprisePolicyTesting } = ChromeUtils.importESModule(
+  "resource://testing-common/EnterprisePolicyTesting.sys.mjs"
+);
+const { AppConstants } = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+);
 
 const HTTP_PORT = 8888;
 const SERVER_ADDRESS = "http://127.0.0.1:8888";
@@ -107,6 +113,35 @@ add_test(function test_ignore_untrusted_source_uris() {
   run_next_test();
 });
 
+// The Extensions policy is implemented in the Firefox-specific Policies module.
+add_task(
+  { skip_if: () => AppConstants.MOZ_APP_NAME != "firefox" },
+  async function test_policy_locked_addon() {
+    _(
+      "Ensures that a policy-locked add-on may not be disabled or uninstalled."
+    );
+
+    const ID = "locked@tests.mozilla.org";
+
+    // setupPolicyEngineWithJson waits on an observer that is not registered
+    // until the policy service is first instantiated.
+    Cc["@mozilla.org/enterprisepolicies;1"].getService(Ci.nsIObserver);
+
+    await EnterprisePolicyTesting.setupPolicyEngineWithJson({
+      policies: { Extensions: { Locked: [ID] } },
+    });
+
+    Assert.ok(!AddonUtils.canDisableAddon(ID));
+    Assert.ok(!AddonUtils.canUninstallAddon(ID));
+    Assert.ok(
+      AddonUtils.canDisableAddon("other@tests.mozilla.org"),
+      "Other add-ons are unaffected"
+    );
+
+    await EnterprisePolicyTesting.setupPolicyEngineWithJson("");
+  }
+);
+
 add_task(async function test_source_uri_rewrite() {
   _("Ensure that a 'src=api' query string is rewritten to 'src=sync'");
 
diff --git a/src/zen/tests/mochitests/sync/test_addons_store.js b/src/zen/tests/mochitests/sync/test_addons_store.js
index 660b13e20..090369f45 100644
--- a/src/zen/tests/mochitests/sync/test_addons_store.js
+++ b/src/zen/tests/mochitests/sync/test_addons_store.js
@@ -12,6 +12,12 @@ const { Service } = ChromeUtils.importESModule(
 const { SyncedRecordsTelemetry } = ChromeUtils.importESModule(
   "resource://services-sync/telemetry.sys.mjs"
 );
+const { EnterprisePolicyTesting } = ChromeUtils.importESModule(
+  "resource://testing-common/EnterprisePolicyTesting.sys.mjs"
+);
+const { AppConstants } = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+);
 
 const HTTP_PORT = 8888;
 
@@ -798,6 +804,39 @@ add_task(async function test_wipe_and_install() {
   await promiseStopServer(server);
 });
 
+// The Extensions policy is implemented in the Firefox-specific Policies module.
+add_task(
+  { skip_if: () => AppConstants.MOZ_APP_NAME != "firefox" },
+  async function test_locked_by_policy() {
+    _("Ensure sync can't disable or uninstall an add-on locked by policy.");
+
+    let addon = await installAddon(XPIS.test_addon1, reconciler);
+    await EnterprisePolicyTesting.setupPolicyEngineWithJson({
+      policies: { Extensions: { Locked: [ID1] } },
+    });
+
+    let countTelemetry = new SyncedRecordsTelemetry();
+    let record = createRecordForThisApp(addon.syncGUID, ID1, false, false);
+    let failed = await store.applyIncomingBatch([record], countTelemetry);
+    Assert.equal(0, failed.length);
+    addon = await AddonManager.getAddonByID(ID1);
+    Assert.ok(!addon.userDisabled, "locked add-on was not disabled");
+
+    record = createRecordForThisApp(addon.syncGUID, ID1, true, true);
+    failed = await store.applyIncomingBatch([record], countTelemetry);
+    Assert.equal(0, failed.length);
+    addon = await AddonManager.getAddonByID(ID1);
+    Assert.ok(addon, "locked add-on was not uninstalled");
+
+    await store.wipe();
+    addon = await AddonManager.getAddonByID(ID1);
+    Assert.ok(addon, "locked add-on survived a wipe");
+
+    await EnterprisePolicyTesting.setupPolicyEngineWithJson("");
+    await uninstallAddon(addon, reconciler);
+  }
+);
+
 // STR for what this is testing:
 // * Either:
 //   * Install then remove an addon, then delete addons.json from the profile
diff --git a/src/zen/tests/mochitests/sync/test_bridged_engine.js b/src/zen/tests/mochitests/sync/test_bridged_engine.js
index f0c49977b..8a9c31684 100644
--- a/src/zen/tests/mochitests/sync/test_bridged_engine.js
+++ b/src/zen/tests/mochitests/sync/test_bridged_engine.js
@@ -26,16 +26,12 @@ add_task(async function test_interface() {
       this.wasWiped = false;
     }
 
-    // `mozIBridgedSyncEngine` methods.
+    // Bridged engine methods.
 
     lastSync() {
       return this.lastSyncMillis;
     }
 
-    setLastSync(millis) {
-      this.lastSyncMillis = millis;
-    }
-
     resetSyncId() {
       return this.syncID;
     }
@@ -53,7 +49,8 @@ add_task(async function test_interface() {
       this.incomingEnvelopes.push(...envelopes.map(r => JSON.parse(r)));
     }
 
-    apply() {
+    apply(serverModifiedMillis) {
+      this.lastSyncMillis = serverModifiedMillis;
       let outgoingEnvelopes = [
         {
           id: "hanson",
@@ -79,6 +76,7 @@ add_task(async function test_interface() {
     }
 
     setUploaded(millis, ids) {
+      this.lastSyncMillis = millis;
       this.uploadedIDs.push(...ids);
     }
 
@@ -86,6 +84,10 @@ add_task(async function test_interface() {
       this.wasSyncFinished = true;
     }
 
+    resetLastSync() {
+      this.lastSyncMillis = 0;
+    }
+
     reset() {
       this.clear();
       this.wasReset = true;
diff --git a/src/zen/tests/mochitests/sync/test_extension_storage_engine.js b/src/zen/tests/mochitests/sync/test_extension_storage_engine.js
index 65194b858..f145ef9e2 100644
--- a/src/zen/tests/mochitests/sync/test_extension_storage_engine.js
+++ b/src/zen/tests/mochitests/sync/test_extension_storage_engine.js
@@ -185,7 +185,7 @@ add_task(async function test_notifyPendingChanges() {
 
 // It's difficult to know what to test - there's already tests for the bridged
 // engine etc - so we just try and check that this engine conforms to the
-// mozIBridgedSyncEngine interface guarantees.
+// bridged engine interface guarantees.
 add_task(async function test_engine() {
   // Forcibly set the bridged engine in the engine manager. the reason we do
   // this, unlike the other tests where we just create the engine, is so that
@@ -200,13 +200,6 @@ add_task(async function test_engine() {
   await engine.resetLocalSyncID();
   Assert.notEqual(await engine.getSyncID(), null);
 
-  Assert.equal(await engine.getLastSync(), 0);
-  // lastSync is seconds on this side of the world, but milli-seconds on the other.
-  await engine.setLastSync(1234.567);
-  // should have 2 digit precision.
-  Assert.equal(await engine.getLastSync(), 1234.57);
-  await engine.setLastSync(0);
-
   // Set some data.
   await extensionStorageSync.set({ id: "ext-2" }, { ext_2_key: "ext_2_value" });
   // Now do a sync with out regular test server.
diff --git a/src/zen/tests/mochitests/sync/test_tab_quickwrite.js b/src/zen/tests/mochitests/sync/test_tab_quickwrite.js
index 36eac5a5c..635858568 100644
--- a/src/zen/tests/mochitests/sync/test_tab_quickwrite.js
+++ b/src/zen/tests/mochitests/sync/test_tab_quickwrite.js
@@ -146,7 +146,7 @@ add_task(async function test_tab_quickwrite_keeps_old_tabs() {
 
   // This test can be flakey because sometimes we are so fast we think there is nothing to do.
   // Resetting the last sync time here ensures we always fetch records from the server.
-  engine.setLastSync(0);
+  await engine.resetLastSync();
   await Service.sync({ engines: ["tabs"] });
 
   // collection should now have 2 records - ours and the pretend remote one we inserted.
diff --git a/src/zen/tests/mochitests/tabMediaIndicator/browser.toml b/src/zen/tests/mochitests/tabMediaIndicator/browser.toml
index 6754a3dd9..4b221ad11 100644
--- a/src/zen/tests/mochitests/tabMediaIndicator/browser.toml
+++ b/src/zen/tests/mochitests/tabMediaIndicator/browser.toml
@@ -1,4 +1,7 @@
 [DEFAULT]
+prefs = [
+  "zen.window-sync.enabled=false",
+]
 subsuite = "media-bc"
 tags = "audiochannel"
 support-files = [
diff --git a/src/zen/tests/pinned/browser_issue_8726.js b/src/zen/tests/pinned/browser_issue_8726.js
index 38d522944..ca9f655bf 100644
--- a/src/zen/tests/pinned/browser_issue_8726.js
+++ b/src/zen/tests/pinned/browser_issue_8726.js
@@ -4,7 +4,7 @@
 "use strict";
 
 const { TabStateFlusher } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+  "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
 );
 
 async function makeNewEmptyTab() {
diff --git a/src/zen/tests/pinned/browser_pinned_edit_url.js b/src/zen/tests/pinned/browser_pinned_edit_url.js
index dae86fa9e..e631a8740 100644
--- a/src/zen/tests/pinned/browser_pinned_edit_url.js
+++ b/src/zen/tests/pinned/browser_pinned_edit_url.js
@@ -96,7 +96,7 @@ add_task(async function test_EditPinnedUrl_ActiveTabNavigates() {
   const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
   try {
     await gZenPinnedTabManager.editPinnedUrl(tab);
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => tab.linkedBrowser.currentURI.spec === editedUrl,
       "the active pinned tab to navigate to the edited URL"
     );
diff --git a/src/zen/tests/pinned/browser_pinned_reset_button.js b/src/zen/tests/pinned/browser_pinned_reset_button.js
index 4691c0980..76d9fc515 100644
--- a/src/zen/tests/pinned/browser_pinned_reset_button.js
+++ b/src/zen/tests/pinned/browser_pinned_reset_button.js
@@ -143,8 +143,10 @@ add_task(async function test_Hover_SublabelChangesWithAccelKey() {
       type: "mouseover",
     });
 
+    // Hovering without Accel leaves the default sublabel in place, so
+    // _setResetPinSublabel intentionally skips redundant setArgs calls.
     Assert.equal(
-      sublabelArgs.at(-1),
+      document.l10n.getAttributes(label).args.tabSubtitle,
       "zen-default-pinned",
       "Sublabel should show default text on hover without Accel"
     );
diff --git a/src/zen/tests/share/browser_share_serialize.js b/src/zen/tests/share/browser_share_serialize.js
index 88b1bb77b..ff7a25f5f 100644
--- a/src/zen/tests/share/browser_share_serialize.js
+++ b/src/zen/tests/share/browser_share_serialize.js
@@ -72,11 +72,7 @@ add_task(async function test_space_serialization() {
 
   const [folderItem, pinnedItem, splitItem, normalItem] = item.items;
   Assert.equal(folderItem.name, "Docs");
-  Assert.equal(
-    folderItem.icon,
-    "chrome://browser/skin/zen-icons/selectable/star.svg",
-    "the custom folder icon is shared"
-  );
+  Assert.ok(!("icon" in folderItem), "folder icons are not shared");
   Assert.equal(folderItem.items.length, 1, "folder keeps its tab");
   Assert.ok(pinnedItem.isPinned, "loose pinned tabs carry isPinned");
   Assert.ok(
diff --git a/src/zen/tests/site_control/browser_site_control_header_buttons.js b/src/zen/tests/site_control/browser_site_control_header_buttons.js
index be61b14f6..0e848e2c7 100644
--- a/src/zen/tests/site_control/browser_site_control_header_buttons.js
+++ b/src/zen/tests/site_control/browser_site_control_header_buttons.js
@@ -65,7 +65,7 @@ add_task(async function test_bookmark_button_reflects_starred_state() {
       url: HTTPS_PAGE,
       title: "test-bookmark",
     });
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => BookmarkingUI.star?.hasAttribute("starred"),
       "BookmarkingUI picks up the new bookmark"
     );
diff --git a/src/zen/tests/site_control/browser_site_control_manage_addons.js b/src/zen/tests/site_control/browser_site_control_manage_addons.js
index 7f243db28..40b56d240 100644
--- a/src/zen/tests/site_control/browser_site_control_manage_addons.js
+++ b/src/zen/tests/site_control/browser_site_control_manage_addons.js
@@ -31,7 +31,7 @@ add_task(async function test_manage_addons_opens_addons_manager() {
       "about:addons opened in a new tab"
     );
 
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => siteDataPanel().state === "closed",
       "panel auto-closes after opening the addons manager"
     );
diff --git a/src/zen/tests/site_control/browser_site_control_shows_installed_addons.js b/src/zen/tests/site_control/browser_site_control_shows_installed_addons.js
index 52ff61097..278914534 100644
--- a/src/zen/tests/site_control/browser_site_control_shows_installed_addons.js
+++ b/src/zen/tests/site_control/browser_site_control_shows_installed_addons.js
@@ -34,7 +34,7 @@ add_task(async function test_panel_lists_installed_addons() {
   try {
     await openSiteDataPanel();
 
-    await BrowserTestUtils.waitForCondition(() => {
+    await TestUtils.waitForCondition(() => {
       const ids = Array.from(addonItemsInPanel()).map(el =>
         el.getAttribute("data-extensionid")
       );
@@ -85,7 +85,7 @@ add_task(async function test_panel_drops_uninstalled_addon() {
 
   try {
     await openSiteDataPanel();
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () =>
         siteDataPanel().querySelector(
           `.unified-extensions-item[data-extensionid="${ext.id}"]`
diff --git a/src/zen/tests/site_control/browser_site_data_permission_toggle.js b/src/zen/tests/site_control/browser_site_data_permission_toggle.js
index 228a5129d..9f308aae9 100644
--- a/src/zen/tests/site_control/browser_site_data_permission_toggle.js
+++ b/src/zen/tests/site_control/browser_site_data_permission_toggle.js
@@ -37,7 +37,7 @@ add_task(async function test_toggling_permission_flips_ui_and_store() {
     );
     EventUtils.synthesizeMouseAtCenter(label, {});
 
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => geoItem.getAttribute("state") === "block",
       "row flips to the block state after the click"
     );
diff --git a/src/zen/tests/space_routing/browser_space_routing_on_add_tab.js b/src/zen/tests/space_routing/browser_space_routing_on_add_tab.js
index 8fa66ceaa..2f77f15d9 100644
--- a/src/zen/tests/space_routing/browser_space_routing_on_add_tab.js
+++ b/src/zen/tests/space_routing/browser_space_routing_on_add_tab.js
@@ -3,7 +3,7 @@
 
 "use strict";
 
-const TARGET_WS = { uuid: "ws-target", containerTabId: 7 };
+const TARGET_WS = { uuid: "ws-target", containerTabId: 7, name: "Target" };
 
 add_setup(async function () {
   clearAllRoutes();
@@ -32,6 +32,7 @@ add_task(async function test_onBeforeAddTab_resolves_container_for_match() {
       userContextId: TARGET_WS.containerTabId,
       isRouteFound: true,
       targetRoute: TARGET_WS.uuid,
+      targetWorkspaceName: TARGET_WS.name,
     },
     "A matching route resolves to the workspace's containerTabId"
   );
@@ -54,6 +55,7 @@ add_task(async function test_onBeforeAddTab_no_match_returns_no_route() {
       userContextId: null,
       isRouteFound: false,
       targetRoute: "most-recent-space",
+      targetWorkspaceName: null,
     },
     "An unmatched URL (most-recent-space) reports no container and no route"
   );
@@ -81,6 +83,7 @@ add_task(async function test_onBeforeAddTab_route_to_missing_workspace() {
       userContextId: null,
       isRouteFound: false,
       targetRoute: "ws-does-not-exist",
+      targetWorkspaceName: null,
     },
     "A route to a non-existent workspace yields no container and no route"
   );
@@ -108,6 +111,7 @@ add_task(async function test_onBeforeAddTab_skips_special_tab_options() {
         userContextId: null,
         isRouteFound: false,
         targetRoute: null,
+        targetWorkspaceName: null,
       },
       `Option '${skipOption}' skips routing even though a rule matches`
     );
@@ -136,6 +140,7 @@ add_task(async function test_onBeforeAddTab_skips_until_startup_ready() {
       userContextId: null,
       isRouteFound: false,
       targetRoute: null,
+      targetWorkspaceName: null,
     },
     "While gZenStartup.isReady is false (session restore), routing is skipped"
   );
diff --git a/src/zen/tests/spaces/browser_select_tab_switches_space.js b/src/zen/tests/spaces/browser_select_tab_switches_space.js
index 4fd738f17..a4046308c 100644
--- a/src/zen/tests/spaces/browser_select_tab_switches_space.js
+++ b/src/zen/tests/spaces/browser_select_tab_switches_space.js
@@ -8,6 +8,9 @@ function fakeTab(workspaceId) {
     getAttribute(name) {
       return name === "zen-workspace-id" ? workspaceId : null;
     },
+    hasAttribute(name) {
+      return this.getAttribute(name) !== null;
+    },
   };
 }
 
diff --git a/src/zen/tests/spaces/head.js b/src/zen/tests/spaces/head.js
index 4ecb614ee..22ce7c474 100644
--- a/src/zen/tests/spaces/head.js
+++ b/src/zen/tests/spaces/head.js
@@ -18,23 +18,23 @@ const HTTPSROOT = ROOT.replace(
 );
 
 const { SessionSaver } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionSaver.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionSaver.sys.mjs"
 );
 const { SessionFile } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/SessionFile.sys.mjs"
+  "moz-src:///browser/components/sessionstore/SessionFile.sys.mjs"
 );
 const { TabState } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/TabState.sys.mjs"
+  "moz-src:///browser/components/sessionstore/TabState.sys.mjs"
 );
 const { TabStateFlusher } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+  "moz-src:///browser/components/sessionstore/TabStateFlusher.sys.mjs"
 );
 const { SessionStoreTestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/SessionStoreTestUtils.sys.mjs"
 );
 
 const { PageWireframes } = ChromeUtils.importESModule(
-  "resource:///modules/sessionstore/PageWireframes.sys.mjs"
+  "moz-src:///browser/components/sessionstore/PageWireframes.sys.mjs"
 );
 
 const ss = SessionStore;
diff --git a/src/zen/tests/tabs/browser_drag_drop_vertical.js b/src/zen/tests/tabs/browser_drag_drop_vertical.js
index 5a2eb476f..dd618f742 100644
--- a/src/zen/tests/tabs/browser_drag_drop_vertical.js
+++ b/src/zen/tests/tabs/browser_drag_drop_vertical.js
@@ -100,7 +100,7 @@ async function ensureNotOverflowing() {
     window.resizeBy(0, increaseBy);
   }
 
-  await BrowserTestUtils.waitForCondition(
+  await TestUtils.waitForCondition(
     () => !gBrowser.tabContainer.arrowScrollbox.overflowing,
     "tabs scrollbox should not be overflowing",
     100,
diff --git a/src/zen/tests/tabs/browser_tabs_cycle_by_attribute.js b/src/zen/tests/tabs/browser_tabs_cycle_by_attribute.js
index acd73939c..43d38ce92 100644
--- a/src/zen/tests/tabs/browser_tabs_cycle_by_attribute.js
+++ b/src/zen/tests/tabs/browser_tabs_cycle_by_attribute.js
@@ -39,7 +39,7 @@ add_setup(async () => {
   ]);
 
   gZenPinnedTabManager.addToEssentials(tabs.slice(0, 3));
-  await BrowserTestUtils.waitForCondition(
+  await TestUtils.waitForCondition(
     () => tabs.slice(0, 3).every(tab => tab.hasAttribute("zen-essential")),
     "all essentials ready"
   );
diff --git a/src/zen/tests/tabs/head.js b/src/zen/tests/tabs/head.js
index b4934d105..9a863ec1e 100644
--- a/src/zen/tests/tabs/head.js
+++ b/src/zen/tests/tabs/head.js
@@ -323,11 +323,11 @@ async function dragAndDrop(
   // Ensure dnd suppression is cleared.
   EventUtils.synthesizeMouseAtCenter(tab2, { type: "mouseup" }, destWindow);
   if (!copy && destWindow == origWindow) {
-    await BrowserTestUtils.waitForCondition(() => {
+    await TestUtils.waitForCondition(() => {
       return tab1.elementIndex != originalIndex;
     }, "Waiting for tab position to be updated");
   } else if (destWindow != origWindow) {
-    await BrowserTestUtils.waitForCondition(
+    await TestUtils.waitForCondition(
       () => tab1.closing,
       "Waiting for tab closing"
     );
diff --git a/src/zen/welcome/ZenWelcome.mjs b/src/zen/welcome/ZenWelcome.mjs
index 322427910..1af5830ec 100644
--- a/src/zen/welcome/ZenWelcome.mjs
+++ b/src/zen/welcome/ZenWelcome.mjs
@@ -424,7 +424,7 @@
         }))
       );
       const { TabStateCache } = ChromeUtils.importESModule(
-        "resource:///modules/sessionstore/TabStateCache.sys.mjs"
+        "moz-src:///browser/components/sessionstore/TabStateCache.sys.mjs"
       );
       for (const app of apps) {
         const tab = window.gBrowser.addTrustedTab(app.url, {
diff --git a/surfer.json b/surfer.json
index f409310f1..75b5d5971 100644
--- a/surfer.json
+++ b/surfer.json
@@ -6,7 +6,7 @@
   "version": {
     "product": "firefox",
     "version": "155.0.1",
-    "candidate": "155.0.1",
+    "candidate": "156.0",
     "candidateBuild": 1
   },
   "buildOptions": {