diff --git a/docs/side-panels.md b/docs/side-panels.md
deleted file mode 100644
index 13f4c7f2e..000000000
--- a/docs/side-panels.md
+++ /dev/null
@@ -1,15 +0,0 @@
-# Zen Side Panels
-
-The `zen.sidepanels.data` configuration will be a JSON string that follows the following data:
-
-```json
-{
-  "data": {
-    "p1": {
-      "url": "https://google.com",
-      "ua": false // "ua" may not be declared! (default: false)
-    }
-  },
-  "index": ["p1"]
-}
-```
diff --git a/l10n b/l10n
index 4094426d2..91a004c86 160000
--- a/l10n
+++ b/l10n
@@ -1 +1 @@
-Subproject commit 4094426d24cf3e131b5a07775478ed893112e9da
+Subproject commit 91a004c86085696aff68902dbed72504a0500f75
diff --git a/src/browser/app/profile/zen-browser.js b/src/browser/app/profile/zen-browser.js
index dd2df31dd..fb1cf3da3 100644
--- a/src/browser/app/profile/zen-browser.js
+++ b/src/browser/app/profile/zen-browser.js
@@ -184,13 +184,6 @@ pref('zen.pinned-tab-manager.close-shortcut-behavior', 'reset-unload-switch');
 // TODO: Check this out!
 pref("browser.profiles.enabled", false);
 
-// Zen webpanels (calling it sidebar due to legacy reasons)
-pref('zen.sidebar.data', "{\"data\":\n {\"p1\":{\n   \"url\":\"https://www.wikipedia.org/\"\n  },\n\"p2\":{\n   \"url\":\"https://m.twitter.com/\",\n\"ua\": true\n  },\n\"p3\": {\n   \"url\": \"https://www.youtube.com/\",\n\"ua\": true\n},\n\"p4\": {\n   \"url\": \"https://translate.google.com/\",\n\"ua\": true\n},\n\"p5\": {\n   \"url\": \"https://todoist.com/\",\n\"ua\": true\n}},\n\"index\":[\"p1\",\"p2\",\"p3\",\"p4\",\"p5\"]}");
-pref('zen.sidebar.enabled', true);
-pref('zen.sidebar.close-on-blur', true);
-pref('zen.sidebar.max-webpanels', 8);
-pref('zen.sidebar.use-google-favicons', true);
-
 // Zen Split View
 pref('zen.splitView.enable-tab-drop', true);
 pref('zen.splitView.min-resize-width', 7);
diff --git a/src/browser/base/content/ZenUIManager.mjs b/src/browser/base/content/ZenUIManager.mjs
index b1283fad6..df822eb5c 100644
--- a/src/browser/base/content/ZenUIManager.mjs
+++ b/src/browser/base/content/ZenUIManager.mjs
@@ -334,7 +334,7 @@ var gZenVerticalTabsManager = {
                 type="checkbox"
                 ${Services.prefs.getBoolPref(kConfigKey) ? 'checked="true"' : ''}
                 data-lazy-l10n-id="zen-toolbar-context-tabs-right"
-                oncommand="gZenVerticalTabsManager.toggleTabsOnRight();"
+                command="cmd_zenToggleTabsOnRight"
         />
     `);
     document.getElementById('viewToolbarsMenuSeparator').before(fragment);
diff --git a/src/browser/base/content/browser-box-inc-xhtml.patch b/src/browser/base/content/browser-box-inc-xhtml.patch
index 3310c63c3..42dc4390d 100644
--- a/src/browser/base/content/browser-box-inc-xhtml.patch
+++ b/src/browser/base/content/browser-box-inc-xhtml.patch
@@ -1,12 +1,11 @@
 diff --git a/browser/base/content/browser-box.inc.xhtml b/browser/base/content/browser-box.inc.xhtml
-index 2ca8bdd2674fb4addf3bbf94ff17abc5c93c6293..49c772ae71e6b3793ff806d22197d3028ff4385f 100644
+index 2ca8bdd2674fb4addf3bbf94ff17abc5c93c6293..dd965d8d190e8cdacbeb3d80995ad1a906e64079 100644
 --- a/browser/base/content/browser-box.inc.xhtml
 +++ b/browser/base/content/browser-box.inc.xhtml
-@@ -26,7 +26,14 @@
+@@ -26,7 +26,13 @@
      <splitter id="sidebar-splitter" class="chromeclass-extrachrome sidebar-splitter" resizebefore="sibling" resizeafter="none" hidden="true"/>
      <box id="after-splitter"></box>
    </div>
-+#include zen-sidebar-panel.inc.xhtml
 +<vbox flex="1" id="zen-appcontent-wrapper">
 +<html:div id="zen-appcontent-navbar-container"></html:div>
 +<hbox id="zen-tabbox-wrapper" flex="1">
diff --git a/src/browser/base/content/browser-sets-inc.patch b/src/browser/base/content/browser-sets-inc.patch
index c4bb1bffb..54f3f1f5d 100644
--- a/src/browser/base/content/browser-sets-inc.patch
+++ b/src/browser/base/content/browser-sets-inc.patch
@@ -1,9 +1,9 @@
 diff --git a/browser/base/content/browser-sets.inc b/browser/base/content/browser-sets.inc
-index 493c593d66883082c2a4df87c4706f919ea675f8..aaaa833b64b0fd890aa2a0794eaeb7e41f002f06 100644
+index 269b025d7fb942602c1b1b6c9747540bcde11375..9dcecfe205cadacace5195ec84d8b2ee292a0632 100644
 --- a/browser/base/content/browser-sets.inc
 +++ b/browser/base/content/browser-sets.inc
-@@ -393,3 +393,4 @@
+@@ -405,3 +405,4 @@
           internal="true"/>
  #endif
    </keyset>
-+  <keyset id="zenKeyset"></keyset>
++#include zen-keysets.inc.xhtml
diff --git a/src/browser/base/content/zen-assets.inc.xhtml b/src/browser/base/content/zen-assets.inc.xhtml
index 3f08b0834..4bd038f68 100644
--- a/src/browser/base/content/zen-assets.inc.xhtml
+++ b/src/browser/base/content/zen-assets.inc.xhtml
@@ -36,7 +36,6 @@ Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/Zen
 Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenThemesImporter.mjs", this);
 Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenCompactMode.mjs", this);
 Services.scriptloader.loadSubScript("chrome://browser/content/ZenUIManager.mjs", this);
-Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenSidebarManager.mjs", this);
 Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenTabUnloader.mjs", this);
 Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenPinnedTabsStorage.mjs", this);
 Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenWorkspacesStorage.mjs", this);
diff --git a/src/browser/base/content/zen-assets.jar.inc.mn b/src/browser/base/content/zen-assets.jar.inc.mn
index 3e5d5e1b0..e78e173a4 100644
--- a/src/browser/base/content/zen-assets.jar.inc.mn
+++ b/src/browser/base/content/zen-assets.jar.inc.mn
@@ -2,6 +2,7 @@
 
         content/browser/zenThemeModifier.js                     (content/zenThemeModifier.js)
         content/browser/ZenStartup.mjs                          (content/ZenStartup.mjs)
+        content/browser/zen-sets.js                             (content/zen-sets.js)
         content/browser/ZenUIManager.mjs                        (content/ZenUIManager.mjs)
         content/browser/ZenCustomizableUI.sys.mjs               (content/ZenCustomizableUI.sys.mjs)
         content/browser/zen-components/ZenUIMigration.mjs       (zen-components/ZenUIMigration.mjs)
@@ -11,7 +12,6 @@
         content/browser/zen-components/ZenWorkspaces.mjs        (zen-components/ZenWorkspaces.mjs)
         content/browser/zen-components/ZenWorkspacesStorage.mjs (zen-components/ZenWorkspacesStorage.mjs)
         content/browser/zen-components/ZenWorkspacesSync.mjs    (zen-components/ZenWorkspacesSync.mjs)
-        content/browser/zen-components/ZenSidebarManager.mjs    (zen-components/ZenSidebarManager.mjs)
         content/browser/zen-components/ZenKeyboardShortcuts.mjs (zen-components/ZenKeyboardShortcuts.mjs)
         content/browser/zen-components/ZenThemesImporter.mjs    (zen-components/ZenThemesImporter.mjs)
         content/browser/zen-components/ZenTabUnloader.mjs       (zen-components/ZenTabUnloader.mjs)
diff --git a/src/browser/base/content/zen-keysets.inc.xhtml b/src/browser/base/content/zen-keysets.inc.xhtml
new file mode 100644
index 000000000..66d8a3a32
--- /dev/null
+++ b/src/browser/base/content/zen-keysets.inc.xhtml
@@ -0,0 +1,48 @@
+<commandset id="zenCommandSet">
+  <command id="cmd_zenCompactModeToggle" />
+  <command id="cmd_zenCompactModeShowSidebar" />
+  <command id="cmd_zenCompactModeShowToolbar" />
+
+  <command id="cmd_zenWorkspaceForward" />
+  <command id="cmd_zenWorkspaceBackward" />
+
+  <command id="cmd_zenSplitViewGrid" />
+  <command id="cmd_zenSplitViewVertical" />
+  <command id="cmd_zenSplitViewHorizontal" />
+  <command id="cmd_zenSplitViewUnsplit" />
+  <command id="cmd_zenSplitViewLinkInNewTab" />
+
+  <!-- Workspace commands -->
+  <command id="cmd_zenWorkspaceSwitch1" />
+  <command id="cmd_zenWorkspaceSwitch2" />
+  <command id="cmd_zenWorkspaceSwitch3" />
+  <command id="cmd_zenWorkspaceSwitch4" />
+  <command id="cmd_zenWorkspaceSwitch5" />
+  <command id="cmd_zenWorkspaceSwitch6" />
+  <command id="cmd_zenWorkspaceSwitch7" />
+  <command id="cmd_zenWorkspaceSwitch8" />
+  <command id="cmd_zenWorkspaceSwitch9" />
+  <command id="cmd_zenWorkspaceSwitch10" />
+
+  <command id="cmd_zenOpenZenThemePicker" />
+  <command id="cmd_zenChangeWorkspaceTabColor" />
+  <command id="cmd_zenToggleTabsOnRight" />
+
+  <command id="cmd_zenReplacePinnedUrlWithCurrent" />
+  <command id="cmd_zenAddToEssentials" />
+  <command id="cmd_zenRemoveFromEssentials" />
+
+  <command id="cmd_zenPinnedTabReset" />
+  <command id="cmd_zenPinnedTabResetNoTab" />
+
+  <command id="cmd_zenToggleSidebar" />
+
+  <command id="cmd_zenCopyCurrentURL" />
+  <command id="cmd_zenCopyCurrentURLMarkdown" />
+
+  <command id="cmd_zenUnloadTab" />
+  <command id="cmd_zenPreventUnloadTab" />
+  <command id="cmd_zenIgnoreUnloadTab" />
+</commandset>
+
+<keyset id="zenKeyset"></keyset>
diff --git a/src/browser/base/content/zen-locales.inc.xhtml b/src/browser/base/content/zen-locales.inc.xhtml
index 5bca39e99..643f917ae 100644
--- a/src/browser/base/content/zen-locales.inc.xhtml
+++ b/src/browser/base/content/zen-locales.inc.xhtml
@@ -1,4 +1,4 @@
-<link rel="localization" href="browser/zen-web-side-panels.ftl"/>
+
 <link rel="localization" href="browser/zen-workspaces.ftl"/>
 <link rel="localization" href="browser/zen-split-view.ftl"/>
 <link rel="localization" href="browser/zen-general.ftl"/>
diff --git a/src/browser/base/content/zen-popupset.inc.xhtml b/src/browser/base/content/zen-popupset.inc.xhtml
index 3550803c2..b63212a9b 100644
--- a/src/browser/base/content/zen-popupset.inc.xhtml
+++ b/src/browser/base/content/zen-popupset.inc.xhtml
@@ -1,86 +1,3 @@
-<menupopup id="zenWebPanelContextMenu"
-            onpopupshowing="if (event.target == this) gZenBrowserManagerSidebar.updateContextMenu(this);"
-            onpopuphidden="if (event.target == this) gZenBrowserManagerSidebar.contextTab = null;">
-  <menuitem id="context_zenUnloadWebPanel" oncommand="gZenBrowserManagerSidebar.contextUnload();" data-l10n-id="zen-web-side-panel-context-unload"/>
-  <menuitem id="context_zenToggleMuteWebPanel" oncommand="gZenBrowserManagerSidebar.contextToggleMuteAudio();"/>
-  <menuitem id="context_zenOpenNewTabWebPanel" oncommand="gZenBrowserManagerSidebar.contextOpenNewTab();" data-l10n-id="zen-web-side-panel-open-in-new-tab"/>
-  <menuseparator/>
-  <menu id="context_zenWebPanelContextInContainer"
-    data-l10n-id="zen-web-side-panel-context-open-in-container-tab"
-    selection-type="single"
-    node-type="link"
-    hide-if-private-browsing="true"
-    hide-if-usercontext-disabled="true">
-    <menupopup oncommand="gZenBrowserManagerSidebar.contextChangeContainerTab(event);"
-          onpopupshowing="return gZenBrowserManagerSidebar.createContainerTabMenu(event);" />
-  </menu>
-  <menuitem id="context_zenToogleUAWebPanel" oncommand="gZenBrowserManagerSidebar.contextToggleUserAgent();"/>
-  <menuseparator/>
-  <menuitem id="context_zenDeleteWebPanel" oncommand="gZenBrowserManagerSidebar.contextDelete();" data-l10n-id="zen-web-side-panel-context-delete"/>
-</menupopup>
-
-<html:template id="template-zen-split-view-modifier">
-<panel id="zenSplitViewModifier"
-  class="panel-no-padding"
-  orient="vertical"
-  role="alertdialog"
-  type="arrow"
-  onpopupshowing="gZenViewSplitter.disableTabRearrangeView();"
-  aria-labelledby="zen-split-view-modifier-header"
-  tabspecific="true">
-  <panelmultiview id="zenSplitViewModifierMultiview"
-    mainViewId="zenSplitViewModifierViewDefault">
-    <panelview id="zenSplitViewModifierViewDefault"
-      class="PanelUI-subView"
-      role="document"
-      mainview-with-header="true"
-      has-custom-header="true">
-      <box id="zenSplitViewModifierHeader"
-        class="panel-header panel-header-with-additional-element panel-header-with-info-button">
-        <html:h1>
-          <html:span data-l10n-id="zen-split-view-modifier-header"></html:span>
-        </html:h1>
-        <toolbarbutton id="zenSplitViewModifierActivateReallocation"
-                        class="panel-info-button"
-                        oncommand="gZenViewSplitter.enableTabRearrangeView();"
-                        data-l10n-id="zen-split-view-modifier-activate-reallocation">
-          <image/>
-        </toolbarbutton>
-      </box>
-      <hbox id="zenSplitViewModifierContent">
-        <vbox>
-          <box class="zen-split-view-modifier-preview grid">
-            <box></box>
-            <box></box>
-            <box></box>
-          </box>
-          <p>Grid Layout</p>
-        </vbox>
-        <vbox>
-          <box class="zen-split-view-modifier-preview vsep">
-            <box></box>
-            <box></box>
-          </box>
-          <p>Vertical</p>
-        </vbox>
-        <vbox>
-          <box class="zen-split-view-modifier-preview hsep">
-            <box></box>
-            <box></box>
-          </box>
-          <p>Horizontal</p>
-        </vbox>
-        <vbox>
-          <box class="zen-split-view-modifier-preview unsplit">
-            <box></box>
-          </box>
-          <p>Unsplit</p>
-        </vbox>
-      </hbox>
-    </panelview>
-  </panelmultiview>
-</panel>
-</html:template>
 
 <panel flip="side" type="arrow" orient="vertical" id="PanelUI-zen-gradient-generator" position="bottomright topright" mainview="true" side="left" onpopuphidden="gZenThemePicker.handlePanelClose();" onpopupshowing="gZenThemePicker.handlePanelOpen();">
   <panelmultiview id="PanelUI-zen-gradient-generator-multiview" mainViewId="PanelUI-zen-gradient-generator-view">
diff --git a/src/browser/base/content/zen-preloaded.inc.xhtml b/src/browser/base/content/zen-preloaded.inc.xhtml
index 1a99f5894..3578e38db 100644
--- a/src/browser/base/content/zen-preloaded.inc.xhtml
+++ b/src/browser/base/content/zen-preloaded.inc.xhtml
@@ -2,6 +2,7 @@
 # the window is fully loaded.
 # Make sure they are loaded before the global-scripts.inc file.
 <script type="text/javascript">
+  Services.scriptloader.loadSubScript("chrome://browser/content/zen-sets.js", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenCommonUtils.mjs", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenKeyboardShortcuts.mjs", this);
   Services.scriptloader.loadSubScript("chrome://browser/content/zen-components/ZenWorkspaces.mjs", this);
diff --git a/src/browser/base/content/zen-sets.js b/src/browser/base/content/zen-sets.js
new file mode 100644
index 000000000..f808ef087
--- /dev/null
+++ b/src/browser/base/content/zen-sets.js
@@ -0,0 +1,92 @@
+document.addEventListener(
+  'MozBeforeInitialXULLayout',
+  () => {
+    // <commandset id="mainCommandSet"> defined in browser-sets.inc
+    document
+      .getElementById('zenCommandSet')
+      // eslint-disable-next-line complexity
+      .addEventListener('command', (event) => {
+        switch (event.target.id) {
+          case 'cmd_zenCompactModeToggle':
+            gZenCompactModeManager.toggle();
+            break;
+          case 'cmd_zenCompactModeShowSidebar':
+            gZenCompactModeManager.toggleSidebar();
+            break;
+          case 'cmd_zenCompactModeShowToolbar':
+            gZenCompactModeManager.toggleToolbar();
+            break;
+          case 'cmd_zenWorkspaceForward':
+            ZenWorkspaces.changeWorkspaceShortcut();
+            break;
+          case 'cmd_zenWorkspaceBackward':
+            ZenWorkspaces.changeWorkspaceShortcut(-1);
+            break;
+          case 'cmd_zenSplitViewGrid':
+            gZenViewSplitter.toggleShortcut('grid');
+            break;
+          case 'cmd_zenSplitViewVertical':
+            gZenViewSplitter.toggleShortcut('vsep');
+            break;
+          case 'cmd_zenSplitViewHorizontal':
+            gZenViewSplitter.toggleShortcut('hsep');
+            break;
+          case 'cmd_zenSplitViewUnsplit':
+            gZenViewSplitter.toggleShortcut('unsplit');
+            break;
+          case 'cmd_zenCopyCurrentURLMarkdown':
+            gZenCommonActions.copyCurrentURLAsMarkdownToClipboard();
+            break;
+          case 'cmd_zenCopyCurrentURL':
+            gZenCommonActions.copyCurrentURLToClipboard();
+            break;
+          case 'cmd_zenPinnedTabReset':
+            gZenPinnedTabManager.resetPinnedTab(gBrowser.selectedTab);
+            break;
+          case 'cmd_zenPinnedTabResetNoTab':
+            gZenPinnedTabManager.resetPinnedTab();
+            break;
+          case 'cmd_zenToggleSidebar':
+            gZenVerticalTabsManager.toggleExpand();
+            break;
+          case 'cmd_zenOpenZenThemePicker':
+            gZenThemePicker.openThemePicker(event);
+            break;
+          case 'cmd_zenChangeWorkspaceTab':
+            ZenWorkspaces.changeTabWorkspace(event.target.getAttribute('zen-workspace-id'));
+            break;
+          case 'cmd_zenToggleTabsOnRight':
+            gZenVerticalTabsManager.toggleTabsOnRight();
+            break;
+          case 'cmd_zenSplitViewLinkInNewTab':
+            gZenViewSplitter.splitLinkInNewTab();
+            break;
+          case 'cmd_zenReplacePinnedUrlWithCurrent':
+            gZenPinnedTabManager.replacePinnedUrlWithCurrent();
+            break;
+          case 'cmd_zenAddToEssentials':
+            gZenPinnedTabManager.addToEssentials();
+            break;
+          case 'cmd_zenRemoveFromEssentials':
+            gZenPinnedTabManager.removeEssentials();
+            break;
+          case 'cmd_zenUnloadTab':
+            gZenTabUnloader.unloadTab();
+            break;
+          case 'cmd_zenPreventUnloadTab':
+            gZenTabUnloader.preventUnloadTab();
+            break;
+          case 'cmd_zenIgnoreUnloadTab':
+            gZenTabUnloader.ignoreUnloadTab();
+            break;
+          default:
+            if (event.target.id.startsWith('cmd_zenWorkspaceSwitch')) {
+              const index = parseInt(event.target.id.replace('cmd_zenWorkspaceSwitch', ''), 10) - 1;
+              ZenWorkspaces.shortcutSwitchTo(index);
+            }
+            break;
+        }
+      });
+  },
+  { once: true }
+);
diff --git a/src/browser/base/content/zen-sidebar-icons.inc.xhtml b/src/browser/base/content/zen-sidebar-icons.inc.xhtml
index 8fd14b854..2d26c0a9c 100644
--- a/src/browser/base/content/zen-sidebar-icons.inc.xhtml
+++ b/src/browser/base/content/zen-sidebar-icons.inc.xhtml
@@ -9,6 +9,5 @@
   context="toolbar-context-menu"
   mode="icons">
   <toolbarbutton removable="true" class="chromeclass-toolbar-additional toolbarbutton-1 zen-sidebar-action-button" id="zen-expand-sidebar-button" data-l10n-id="sidebar-zen-expand" cui-areatype="toolbar" oncommand="gZenVerticalTabsManager.toggleExpand();"></toolbarbutton>
-  <toolbarbutton removable="true" class="toolbarbutton-1 zen-sidebar-action-button zen-compact-mode-ignore" id="zen-sidepanel-button" data-l10n-id="sidebar-zen-sidepanel" onclick="gZenBrowserManagerSidebar.toggle();"></toolbarbutton>
   <toolbarbutton id="zen-workspaces-button" class="chromeclass-toolbar-additional" overflows="false" removable="false"></toolbarbutton>
 </toolbar>
diff --git a/src/browser/base/content/zen-sidebar-panel.inc.xhtml b/src/browser/base/content/zen-sidebar-panel.inc.xhtml
deleted file mode 100644
index e089825f5..000000000
--- a/src/browser/base/content/zen-sidebar-panel.inc.xhtml
+++ /dev/null
@@ -1,34 +0,0 @@
-<hbox id="zen-sidebar-web-panel-wrapper">
-  <box id="zen-sidebar-web-panel" class="chromeclass-extrachrome" hidden="true" persist="pinned style hidden" pinned="true">
-    <toolbar mode="icons" flex="1" id="zen-sidebar-web-header" fullscreentoolbar="true">
-      <hbox>
-        <toolbarbutton id="zen-sidebar-web-panel-back" class="toolbarbutton-1 chromeclass-toolbar-additional" oncommand="gZenBrowserManagerSidebar.back();"/>
-        <toolbarbutton id="zen-sidebar-web-panel-forward" class="toolbarbutton-1 chromeclass-toolbar-additional" oncommand="gZenBrowserManagerSidebar.forward();"/>
-        <toolbarbutton id="zen-sidebar-web-panel-reload" class="toolbarbutton-1 chromeclass-toolbar-additional" oncommand="gZenBrowserManagerSidebar.reload();"/>
-      </hbox>
-      <hbox id="zen-sidebar-web-panel-title" flex="1">
-      </hbox>
-      <hbox>
-        <toolbarbutton id="zen-sidebar-web-panel-home" class="toolbarbutton-1 chromeclass-toolbar-additional" oncommand="gZenBrowserManagerSidebar.home();"/>
-        <toolbarbutton id="zen-sidebar-web-panel-pinned" class="toolbarbutton-1 chromeclass-toolbar-additional" pinned="true" oncommand="gZenBrowserManagerSidebar.togglePinned(this);"/>
-        <toolbarbutton id="zen-sidebar-web-panel-close" class="toolbarbutton-1 chromeclass-toolbar-additional" oncommand="gZenBrowserManagerSidebar.close();"/>
-      </hbox>
-    </toolbar>
-    <vbox id="zen-sidebar-web-panel-browser-containers">
-      <vbox id="zen-sidebar-introduction-panel" hidden="true">
-        <html:h1 data-l10n-id="zen-webpanel-introduction-title"/>
-        <html:p data-l10n-id="zen-webpanel-introduction-description"/>
-      </vbox>
-    </vbox>
-    <toolbar mode="icons" flex="1" id="zen-sidebar-panels-wrapper" fullscreentoolbar="true">
-      <toolbar mode="icons" flex="1" id="zen-sidebar-panels-sites" fullscreentoolbar="true">
-
-      </toolbar>
-      <toolbarbutton id="zen-sidebar-add-panel-button" class="zen-sidebar-panel-button toolbarbutton-1 chromeclass-toolbar-additional" onclick="gZenBrowserManagerSidebar._openAddPanelDialog();"/>
-    </toolbar>
-    <html:span class="zen-sidebar-web-panel-splitter" side="left"></html:span>
-    <html:span class="zen-sidebar-web-panel-splitter" side="right"></html:span>
-    <html:span class="zen-sidebar-web-panel-splitter" orient="horizontal" side="top"></html:span>
-    <html:span class="zen-sidebar-web-panel-splitter" orient="horizontal" side="bottom"></html:span>
-  </box>
-</hbox>
diff --git a/src/browser/base/content/zen-styles/zen-decks.css b/src/browser/base/content/zen-styles/zen-decks.css
index c92fa6216..ffab75cb6 100644
--- a/src/browser/base/content/zen-styles/zen-decks.css
+++ b/src/browser/base/content/zen-styles/zen-decks.css
@@ -106,113 +106,6 @@
   display: flex !important;
 }
 
-/* Split view panel */
-
-#zenSplitViewModifierViewDefault {
-  min-width: 180px;
-  min-height: 180px;
-
-  padding: 15px;
-  padding-top: 12px;
-}
-
-#zenSplitViewModifierContent {
-  display: grid;
-  grid-template-columns: 1fr 1fr;
-  grid-template-rows: 1fr 1fr;
-
-  gap: 15px;
-}
-
-#zenSplitViewModifierContent > vbox {
-  display: flex;
-  align-items: center;
-  flex-direction: column;
-  cursor: pointer;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview {
-  border-radius: 5px;
-  border: 1px solid var(--zen-colors-border);
-  width: 100px;
-  height: 70px;
-  overflow: hidden;
-  padding: 5px;
-  user-select: none;
-  font-weight: 500;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.active {
-  box-shadow: 0 0 0 2px var(--zen-primary-color);
-  border-width: 0px;
-}
-
-#zenSplitViewModifierContent p {
-  margin-top: 5px;
-  margin-bottom: 0;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview {
-  & box {
-    background-color: var(--zen-colors-secondary);
-    border-radius: 3px;
-    width: 100%;
-    height: 100%;
-    transition: 0.1s;
-  }
-
-  &:hover box {
-    background-color: var(--zen-primary-color);
-  }
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.hsep {
-  display: flex;
-  flex-direction: column;
-  justify-content: space-between;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.hsep box:last-child {
-  margin-top: 5px;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.vsep box:last-child {
-  margin-left: 5px;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.grid {
-  display: grid;
-  grid-template-areas: 'a b' 'c b';
-  gap: 5px;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.grid box:nth-child(1) {
-  grid-area: a;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.grid box:nth-child(2) {
-  grid-area: b;
-}
-
-#zenSplitViewModifierContent .zen-split-view-modifier-preview.grid box:nth-child(3) {
-  grid-area: c;
-}
-
-#zenSplitViewModifierHeader {
-  min-height: 0;
-  padding: 0;
-  margin: 0;
-  margin-bottom: 12px;
-}
-
-#zenSplitViewModifierEnabledToast {
-  display: none;
-}
-
-#zenSplitViewModifier:not([has-enabled-realloc])[toast] #zenSplitViewModifierEnabledToast {
-  display: revert;
-}
-
 .zen-view-splitter-header-container {
   position: absolute;
   top: calc(var(--zen-split-column-gap) / -2);
diff --git a/src/browser/base/zen-components/ZenGradientGenerator.mjs b/src/browser/base/zen-components/ZenGradientGenerator.mjs
index 97dce58c9..7e43b36a0 100644
--- a/src/browser/base/zen-components/ZenGradientGenerator.mjs
+++ b/src/browser/base/zen-components/ZenGradientGenerator.mjs
@@ -52,7 +52,7 @@
       const menu = window.MozXULElement.parseXULToFragment(`
         <menuitem id="zenToolbarThemePicker"
                   data-lazy-l10n-id="zen-workspaces-change-gradient"
-                  oncommand="gZenThemePicker.openThemePicker(event);"/>
+                  command="cmd_zenOpenZenThemePicker"/>
       `);
       document.getElementById('toolbar-context-customize').before(menu);
     }
diff --git a/src/browser/base/zen-components/ZenKeyboardShortcuts.mjs b/src/browser/base/zen-components/ZenKeyboardShortcuts.mjs
index 986dd3d26..d0723eaa4 100644
--- a/src/browser/base/zen-components/ZenKeyboardShortcuts.mjs
+++ b/src/browser/base/zen-components/ZenKeyboardShortcuts.mjs
@@ -403,11 +403,7 @@ class KeyShortcut {
     }
     key.setAttribute('modifiers', this.#modifiers.toString());
     if (this.#action) {
-      if (this.#action?.startsWith('code:')) {
-        key.setAttribute('oncommand', this.#action.substring(5));
-      } else {
-        key.setAttribute('command', this.#action);
-      }
+      key.setAttribute('command', this.#action);
     }
     if (this.#disabled) {
       key.setAttribute('disabled', this.#disabled);
@@ -442,6 +438,11 @@ class KeyShortcut {
     return this.#action;
   }
 
+  // Only used for migration!
+  _setAction(action) {
+    this.#action = action;
+  }
+
   getL10NID() {
     return this.#l10nId;
   }
@@ -603,7 +604,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_COMPACT_MODE_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        'code:gZenCompactModeManager.toggle()',
+        'cmd_zenCompactModeToggle',
         'zen-compact-mode-shortcut-toggle'
       )
     );
@@ -614,7 +615,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_COMPACT_MODE_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        'code:gZenCompactModeManager.toggleSidebar()',
+        'cmd_zenCompactModeShowSidebar',
         'zen-compact-mode-shortcut-show-sidebar'
       )
     );
@@ -625,12 +626,12 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_COMPACT_MODE_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        'code:gZenCompactModeManager.toggleToolbar()',
+        'cmd_zenCompactModeShowToolbar',
         'zen-compact-mode-shortcut-show-toolbar'
       )
     );
 
-    // Workspace's keyset
+    // Workspace shortcuts
     for (let i = 10; i > 0; i--) {
       newShortcutList.push(
         new KeyShortcut(
@@ -639,7 +640,7 @@ class ZenKeyboardShortcutsLoader {
           '',
           ZEN_WORKSPACE_SHORTCUTS_GROUP,
           KeyShortcutModifiers.fromObject({}),
-          `code:ZenWorkspaces.shortcutSwitchTo(${i - 1})`,
+          `cmd_zenWorkspaceSwitch${i}`,
           `zen-workspace-shortcut-switch-${i}`
         )
       );
@@ -651,7 +652,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_WORKSPACE_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        'code:ZenWorkspaces.changeWorkspaceShortcut()',
+        'cmd_zenWorkspaceForward',
         'zen-workspace-shortcut-forward'
       )
     );
@@ -662,24 +663,11 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_WORKSPACE_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        'code:ZenWorkspaces.changeWorkspaceShortcut(-1)',
+        'cmd_zenWorkspaceBackward',
         'zen-workspace-shortcut-backward'
       )
     );
 
-    // Other keyset
-    newShortcutList.push(
-      new KeyShortcut(
-        'zen-toggle-web-panel',
-        'P',
-        '',
-        ZEN_OTHER_SHORTCUTS_GROUP,
-        KeyShortcutModifiers.fromObject({ alt: true }),
-        'code:gZenBrowserManagerSidebar.toggle()',
-        'zen-web-panel-shortcut-toggle'
-      )
-    );
-
     // Split view
     newShortcutList.push(
       new KeyShortcut(
@@ -688,7 +676,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_SPLIT_VIEW_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        "code:gZenViewSplitter.toggleShortcut('grid')",
+        'cmd_zenSplitViewGrid',
         'zen-split-view-shortcut-grid'
       )
     );
@@ -699,7 +687,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_SPLIT_VIEW_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        "code:gZenViewSplitter.toggleShortcut('vsep')",
+        'cmd_zenSplitViewVertical',
         'zen-split-view-shortcut-vertical'
       )
     );
@@ -710,7 +698,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_SPLIT_VIEW_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        "code:gZenViewSplitter.toggleShortcut('hsep')",
+        'cmd_zenSplitViewHorizontal',
         'zen-split-view-shortcut-horizontal'
       )
     );
@@ -721,7 +709,7 @@ class ZenKeyboardShortcutsLoader {
         '',
         ZEN_SPLIT_VIEW_SHORTCUTS_GROUP,
         KeyShortcutModifiers.fromObject({ accel: true, alt: true }),
-        "code:gZenViewSplitter.toggleShortcut('unsplit')",
+        'cmd_zenSplitViewUnsplit',
         'zen-split-view-shortcut-unsplit'
       )
     );
@@ -756,7 +744,7 @@ class ZenKeyboardShortcutsLoader {
 }
 
 class ZenKeyboardShortcutsVersioner {
-  static LATEST_KBS_VERSION = 8;
+  static LATEST_KBS_VERSION = 9;
 
   constructor() {}
 
@@ -848,7 +836,7 @@ class ZenKeyboardShortcutsVersioner {
           '',
           ZEN_OTHER_SHORTCUTS_GROUP,
           KeyShortcutModifiers.fromObject({}),
-          'code:gZenPinnedTabManager.resetPinnedTab(gBrowser.selectedTab)',
+          'cmd_zenPinnedTabReset',
           'zen-pinned-tab-shortcut-reset'
         )
       );
@@ -885,7 +873,7 @@ class ZenKeyboardShortcutsVersioner {
           '',
           ZEN_OTHER_SHORTCUTS_GROUP,
           KeyShortcutModifiers.fromObject({ alt: true }),
-          'code:gZenVerticalTabsManager.toggleExpand()',
+          'cmd_zenToggleSidebar',
           'zen-sidebar-shortcut-toggle'
         )
       );
@@ -900,7 +888,7 @@ class ZenKeyboardShortcutsVersioner {
           '',
           ZEN_OTHER_SHORTCUTS_GROUP,
           KeyShortcutModifiers.fromObject({ accel: true, shift: true }),
-          'code:gZenCommonActions.copyCurrentURLToClipboard()',
+          'cmd_zenCopyCurrentURL',
           'zen-text-action-copy-url-shortcut'
         )
       );
@@ -932,11 +920,50 @@ class ZenKeyboardShortcutsVersioner {
           '',
           ZEN_OTHER_SHORTCUTS_GROUP,
           KeyShortcutModifiers.fromObject({ accel: true, shift: true, alt: true }),
-          'code:gZenCommonActions.copyCurrentURLAsMarkdownToClipboard()',
+          'cmd_zenCopyCurrentURLMarkdown',
           'zen-text-action-copy-url-markdown-shortcut'
         )
       );
     }
+    if (version < 9) {
+      // Migrate from version 8 to 9
+      // Due to security concerns, replace "code:" actions with corresponding <command> IDs
+      // we also remove 'zen-toggle-web-panel' since it's not used anymore
+      data = data.filter((shortcut) => shortcut.getID() != 'zen-toggle-web-panel');
+      for (let shortcut of data) {
+        if (shortcut.getAction()?.startsWith('code:')) {
+          const id = shortcut.getID();
+
+          // Map old shortcut IDs to new <command> IDs
+          const commandMap = {
+            'zen-compact-mode-toggle': 'cmd_zenCompactModeToggle',
+            'zen-compact-mode-show-sidebar': 'cmd_zenCompactModeShowSidebar',
+            'zen-compact-mode-show-toolbar': 'cmd_zenCompactModeShowToolbar',
+            'zen-workspace-forward': 'cmd_zenWorkspaceForward',
+            'zen-workspace-backward': 'cmd_zenWorkspaceBackward',
+            'zen-split-view-grid': 'cmd_zenSplitViewGrid',
+            'zen-split-view-vertical': 'cmd_zenSplitViewVertical',
+            'zen-split-view-horizontal': 'cmd_zenSplitViewHorizontal',
+            'zen-split-view-unsplit': 'cmd_zenSplitViewUnsplit',
+            'zen-copy-url': 'cmd_zenCopyCurrentURL',
+            'zen-copy-url-markdown': 'cmd_zenCopyCurrentURLMarkdown',
+            'zen-pinned-tab-reset-shortcut': 'cmd_zenPinnedTabReset',
+            'zen-toggle-sidebar': 'cmd_zenToggleSidebar',
+          };
+
+          // Dynamically handle workspace switch shortcuts (zen-workspace-switch-1 to 10)
+          if (id?.startsWith('zen-workspace-switch-')) {
+            const num = id.replace('zen-workspace-switch-', '');
+            commandMap[id] = `cmd_zenWorkspaceSwitch${num}`;
+          }
+
+          // Replace action if a corresponding command exists
+          if (commandMap[id]) {
+            shortcut._setAction(commandMap[id]);
+          }
+        }
+      }
+    }
     return data;
   }
 }
@@ -944,6 +971,7 @@ class ZenKeyboardShortcutsVersioner {
 var gZenKeyboardShortcutsManager = {
   loader: new ZenKeyboardShortcutsLoader(),
   _hasToLoadDevtools: false,
+  _inlineCommands: [],
 
   beforeInit() {
     if (!this.inBrowserView) {
diff --git a/src/browser/base/zen-components/ZenMediaController.mjs b/src/browser/base/zen-components/ZenMediaController.mjs
index 57bc92cdb..f4e17aab8 100644
--- a/src/browser/base/zen-components/ZenMediaController.mjs
+++ b/src/browser/base/zen-components/ZenMediaController.mjs
@@ -442,9 +442,7 @@ class ZenMediaController {
 
   onMediaFocus() {
     if (!this._currentBrowser) return;
-    const sidebarId = this._currentBrowser.getAttribute('zen-sidebar-id');
-    if (sidebarId) gZenBrowserManagerSidebar.open(sidebarId);
-    else this._currentMediaController?.focus();
+    this._currentMediaController?.focus();
   }
 
   onMediaMute() {
diff --git a/src/browser/base/zen-components/ZenPinnedTabManager.mjs b/src/browser/base/zen-components/ZenPinnedTabManager.mjs
index 69df77ee4..b73a25d27 100644
--- a/src/browser/base/zen-components/ZenPinnedTabManager.mjs
+++ b/src/browser/base/zen-components/ZenPinnedTabManager.mjs
@@ -672,11 +672,11 @@
             <menuitem id="context_zen-replace-pinned-url-with-current"
                       data-lazy-l10n-id="tab-context-zen-replace-pinned-url-with-current"
                       hidden="true"
-                      oncommand="gZenPinnedTabManager.replacePinnedUrlWithCurrent();"/>
+                      command="cmd_zenReplacePinnedUrlWithCurrent"/>
             <menuitem id="context_zen-reset-pinned-tab"
                       data-lazy-l10n-id="tab-context-zen-reset-pinned-tab"
                       hidden="true"
-                      oncommand="gZenPinnedTabManager.resetPinnedTab();"/>
+                      command="cmd_zenPinnedTabResetNoTab"/>
         `);
       document.getElementById('tabContextMenu').appendChild(elements);
 
@@ -684,11 +684,11 @@
             <menuitem id="context_zen-add-essential"
                       data-lazy-l10n-id="tab-context-zen-add-essential"
                       hidden="true"
-                      oncommand="gZenPinnedTabManager.addToEssentials();"/>
+                      command="cmd_zenAddToEssentials"/>
             <menuitem id="context_zen-remove-essential"
                       data-lazy-l10n-id="tab-context-zen-remove-essential"
                       hidden="true"
-                      oncommand="gZenPinnedTabManager.removeEssentials();"/>
+                      command="cmd_zenRemoveFromEssentials"/>
         `);
 
       document.getElementById('context_pinTab')?.before(element);
diff --git a/src/browser/base/zen-components/ZenSidebarManager.mjs b/src/browser/base/zen-components/ZenSidebarManager.mjs
deleted file mode 100644
index 3dfaa8a99..000000000
--- a/src/browser/base/zen-components/ZenSidebarManager.mjs
+++ /dev/null
@@ -1,795 +0,0 @@
-class ZenBrowserManagerSidebar extends ZenDOMOperatedFeature {
-  _sidebarElement = null;
-  _currentPanel = null;
-  _lastOpenedPanel = null;
-  _hasChangedConfig = true;
-  _splitterElement = null;
-  _hSplitterElement = null;
-  _hasRegisteredPinnedClickOutside = false;
-  _isDragging = false;
-  contextTab = null;
-  sidebar = null;
-  forwardButton = null;
-  backButton = null;
-  progressListener = null;
-  _tabBrowserSet = new WeakMap();
-  tabBox;
-
-  DEFAULT_MOBILE_USER_AGENT = `Mozilla/5.0 (Android 12; Mobile; rv:129.0) Gecko/20100101 Firefox/${AppConstants.ZEN_FIREFOX_VERSION}`;
-  MAX_SIDEBAR_PANELS = Services.prefs.getIntPref('zen.sidebar.max-webpanels');
-
-  init() {
-    ChromeUtils.defineLazyGetter(this, 'sidebar', () => document.getElementById('zen-sidebar-web-panel'));
-    ChromeUtils.defineLazyGetter(this, 'forwardButton', () => document.getElementById('zen-sidebar-web-panel-forward'));
-    ChromeUtils.defineLazyGetter(this, 'backButton', () => document.getElementById('zen-sidebar-web-panel-back'));
-    ChromeUtils.defineLazyGetter(this, 'tabBox', () => document.getElementById('tabbrowser-tabbox'));
-
-    this.onlySafeWidthAndHeight();
-
-    this.initProgressListener();
-    this.close(); // avoid caching
-    this.tabBox.prepend(this.sidebarWrapper);
-    this.listenForPrefChanges();
-    this.insertIntoContextMenu();
-    this.addPositioningListeners();
-    this.syncPinnedState();
-  }
-
-  onlySafeWidthAndHeight() {
-    const panel = this.sidebar;
-    const width = panel.style.width;
-    const height = panel.style.height;
-    panel.setAttribute('style', '');
-    panel.style.width = width;
-    panel.style.height = height;
-  }
-
-  initProgressListener() {
-    this.progressListener = {
-      QueryInterface: ChromeUtils.generateQI(['nsIWebProgressListener', 'nsISupportsWeakReference']),
-      onLocationChange: function (aWebProgress, aRequest, aLocation, aFlags) {
-        const browser = this._getCurrentBrowser();
-        if (!browser) return;
-        const forwardDisabled = this.forwardButton.hasAttribute('disabled');
-        const backDisabled = this.backButton.hasAttribute('disabled');
-
-        if (browser.canGoForward === forwardDisabled) {
-          if (browser.canGoForward) {
-            this.forwardButton.removeAttribute('disabled');
-          } else {
-            this.forwardButton.setAttribute('disabled', true);
-          }
-        }
-        if (browser.canGoBack === backDisabled) {
-          if (browser.canGoBack) {
-            this.backButton.removeAttribute('disabled');
-          } else {
-            this.backButton.setAttribute('disabled', true);
-          }
-        }
-      }.bind(gZenBrowserManagerSidebar),
-    };
-  }
-
-  get sidebarData() {
-    let services = Services.prefs.getStringPref('zen.sidebar.data');
-    if (services === '') {
-      return {};
-    }
-    return JSON.parse(services);
-  }
-
-  get shouldCloseOnBlur() {
-    return Services.prefs.getBoolPref('zen.sidebar.close-on-blur');
-  }
-
-  listenForPrefChanges() {
-    Services.prefs.addObserver('zen.sidebar.data', this.handleEvent.bind(this));
-    Services.prefs.addObserver('zen.sidebar.enabled', this.handleEvent.bind(this));
-
-    this.handleEvent();
-  }
-
-  addPositioningListeners() {
-    this.sidebar
-      .querySelectorAll('.zen-sidebar-web-panel-splitter')
-      .forEach((s) => s.addEventListener('mousedown', this.handleSplitterMouseDown.bind(this)));
-    this.sidebarHeader.addEventListener('mousedown', this.handleDragPanel.bind(this));
-    window.addEventListener('resize', this.onWindowResize.bind(this));
-  }
-
-  syncPinnedState() {
-    const sidebar = document.getElementById('zen-sidebar-web-panel');
-    const pinButton = document.getElementById('zen-sidebar-web-panel-pinned');
-
-    if (sidebar.hasAttribute('pinned')) {
-      pinButton.setAttribute('pinned', 'true');
-    } else {
-      pinButton.removeAttribute('pinned');
-    }
-  }
-
-  handleSplitterMouseDown(mouseDownEvent) {
-    if (this._isDragging) return;
-    this._isDragging = true;
-
-    const isHorizontal = mouseDownEvent.target.getAttribute('orient') === 'horizontal';
-    setCursor(isHorizontal ? 'ns-resize' : 'ew-resize');
-    const reverse = ['left', 'top'].includes(mouseDownEvent.target.getAttribute('side'));
-    const direction = isHorizontal ? 'height' : 'width';
-    const axis = isHorizontal ? 'Y' : 'X';
-
-    const computedStyle = window.getComputedStyle(this.sidebar);
-    const maxSize = parseInt(computedStyle.getPropertyValue(`max-${direction}`).match(/(\d+)px/)?.[1]) || Infinity;
-    const minSize = parseInt(computedStyle.getPropertyValue(`min-${direction}`).match(/(\d+)px/)?.[1]) || 0;
-
-    const sidebarSizeStart = this.sidebar.getBoundingClientRect()[direction];
-
-    const startPos = mouseDownEvent[`screen${axis}`];
-
-    const toAdjust = isHorizontal ? 'top' : 'left';
-    const sidebarPosStart = parseInt(this.sidebar.style[toAdjust].match(/\d+/));
-
-    let mouseMove = function (e) {
-      let mouseMoved = e[`screen${axis}`] - startPos;
-      if (reverse) {
-        mouseMoved *= -1;
-      }
-      let newSize = sidebarSizeStart + mouseMoved;
-      let currentMax = maxSize;
-      const wrapperBox = this.sidebarWrapper.getBoundingClientRect();
-      let maxWrapperSize = Infinity;
-      if (this.isFloating) {
-        maxWrapperSize = reverse ? sidebarPosStart + sidebarSizeStart : wrapperBox[direction] - sidebarPosStart;
-      }
-      newSize = Math.max(minSize, Math.min(currentMax, maxWrapperSize, newSize));
-
-      window.requestAnimationFrame(() => {
-        if (reverse) {
-          const actualMoved = newSize - sidebarSizeStart;
-          this.sidebar.style[toAdjust] = sidebarPosStart - actualMoved + 'px';
-        }
-        this.sidebar.style[direction] = `${newSize}px`;
-      });
-    }.bind(this);
-
-    document.addEventListener('mousemove', mouseMove);
-    document.addEventListener(
-      'mouseup',
-      () => {
-        document.removeEventListener('mousemove', mouseMove);
-        this._isDragging = false;
-        setCursor('auto');
-      },
-      { once: true }
-    );
-  }
-
-  handleDragPanel(mouseDownEvent) {
-    if (this.sidebarHeaderButtons.find((b) => b.contains(mouseDownEvent.target))) {
-      return;
-    }
-    this._isDragging = true;
-    const startTop = this.sidebar.style.top?.match(/\d+/)?.[0] || 0;
-    const startLeft = this.sidebar.style.left?.match(/\d+/)?.[0] || 0;
-
-    const sidebarBBox = this.sidebar.getBoundingClientRect();
-    const sideBarHeight = sidebarBBox.height;
-    const sideBarWidth = sidebarBBox.width;
-
-    const topMouseOffset = startTop - mouseDownEvent.screenY;
-    const leftMouseOffset = startLeft - mouseDownEvent.screenX;
-    const moveListener = (mouseMoveEvent) => {
-      window.requestAnimationFrame(() => {
-        let top = mouseMoveEvent.clientY + topMouseOffset;
-        let left = mouseMoveEvent.clientX + leftMouseOffset;
-
-        const wrapperBounds = this.sidebarWrapper.getBoundingClientRect();
-        top = Math.max(0, Math.min(top, wrapperBounds.height - sideBarHeight));
-        left = Math.max(0, Math.min(left, wrapperBounds.width - sideBarWidth));
-
-        this.sidebar.style.top = top + 'px';
-        this.sidebar.style.left = left + 'px';
-      });
-    };
-
-    document.addEventListener('mousemove', moveListener);
-    document.addEventListener(
-      'mouseup',
-      () => {
-        document.removeEventListener('mousemove', moveListener);
-        this._isDragging = false;
-      },
-      { once: true }
-    );
-  }
-
-  onWindowResize() {
-    if (!this.isFloating) return;
-    const top = parseInt(this.sidebar.style.top?.match(/\d+/)?.[0] || 0);
-    const left = parseInt(this.sidebar.style.left?.match(/\d+/)?.[0] || 0);
-    const wrapperRect = this.sidebarWrapper.getBoundingClientRect();
-    const sidebarRect = this.sidebar.getBoundingClientRect();
-
-    if (sidebarRect.height < wrapperRect.height && top + sidebarRect.height > wrapperRect.height) {
-      this.sidebar.style.top = wrapperRect.height - sidebarRect.height + 'px';
-    }
-    if (sidebarRect.width < wrapperRect.width && left + sidebarRect.width > wrapperRect.width) {
-      this.sidebar.style.left = wrapperRect.width - sidebarRect.width + 'px';
-    }
-  }
-
-  get isFloating() {
-    return document.getElementById('zen-sidebar-web-panel').hasAttribute('pinned');
-  }
-
-  handleEvent() {
-    this._hasChangedConfig = true;
-    this.update();
-    this._hasChangedConfig = false;
-
-    // https://stackoverflow.com/questions/11565471/removing-event-listener-which-was-added-with-bind
-    var clickOutsideHandler = this._handleClickOutside.bind(this);
-    let isFloating = this.isFloating;
-    if (isFloating && !this._hasRegisteredPinnedClickOutside) {
-      document.addEventListener('mouseup', clickOutsideHandler);
-      this._hasRegisteredPinnedClickOutside = true;
-    } else if (!isFloating && this._hasRegisteredPinnedClickOutside) {
-      document.removeEventListener('mouseup', clickOutsideHandler);
-      this._hasRegisteredPinnedClickOutside = false;
-    }
-
-    const button = document.getElementById('zen-sidepanel-button');
-    if (!button) return;
-    if (Services.prefs.getBoolPref('zen.sidebar.enabled')) {
-      button.removeAttribute('hidden');
-    } else {
-      button.setAttribute('hidden', 'true');
-      this._closeSidebarPanel();
-      return;
-    }
-  }
-
-  _handleClickOutside(event) {
-    if (!this.sidebar.hasAttribute('pinned') || this._isDragging || !this.shouldCloseOnBlur) {
-      return;
-    }
-    let target = event.target;
-    const closestSelector = [
-      '#zen-sidebar-web-panel',
-      '#zen-sidebar-panels-wrapper',
-      '#zenWebPanelContextMenu',
-      '#zen-sidebar-web-panel-splitter',
-      '#contentAreaContextMenu',
-      '#zen-sidepanel-button',
-    ].join(', ');
-    if (target.closest(closestSelector)) {
-      return;
-    }
-    this.close();
-  }
-
-  toggle() {
-    if (!this._currentPanel) {
-      this._currentPanel = this._lastOpenedPanel;
-    }
-    if (document.getElementById('zen-sidebar-web-panel').hasAttribute('hidden')) {
-      this.open();
-      return;
-    }
-    this.close();
-  }
-
-  open(id = null) {
-    let sidebar = document.getElementById('zen-sidebar-web-panel');
-    if (id) this._currentPanel = id;
-
-    sidebar.removeAttribute('hidden');
-    this.update();
-  }
-
-  update() {
-    this._updateWebPanels();
-    this._updateSidebarButton();
-    this._updateWebPanel();
-    this._updateButtons();
-  }
-
-  _updateSidebarButton() {
-    let button = document.getElementById('zen-sidepanel-button');
-    if (!button) return;
-    if (!document.getElementById('zen-sidebar-web-panel').hasAttribute('hidden')) {
-      button.setAttribute('open', 'true');
-    } else {
-      button.removeAttribute('open');
-    }
-  }
-
-  _updateWebPanels() {
-    if (Services.prefs.getBoolPref('zen.sidebar.enabled')) {
-      this.sidebarElement.removeAttribute('hidden');
-    } else {
-      this.sidebarElement.setAttribute('hidden', 'true');
-      this._closeSidebarPanel();
-      return;
-    }
-
-    // Don't reload content if at least one of the panel tabs was loaded
-    if (this._lastOpenedPanel) {
-      return;
-    }
-
-    let data = this.sidebarData;
-    if (!data.data || !data.index) {
-      return;
-    }
-    this.sidebarElement.innerHTML = '';
-    for (let site of data.index) {
-      let panel = data.data[site];
-      if (!panel || !panel.url) {
-        continue;
-      }
-      let button = document.createXULElement('toolbarbutton');
-      button.classList.add('zen-sidebar-panel-button', 'toolbarbutton-1', 'chromeclass-toolbar-additional');
-      button.setAttribute('flex', '1');
-      button.setAttribute('zen-sidebar-id', site);
-      button.setAttribute('context', 'zenWebPanelContextMenu');
-      this._getWebPanelIcon(panel.url, button);
-      button.addEventListener('click', this._handleClick.bind(this));
-      button.addEventListener('dragstart', this._handleDragStart.bind(this));
-      button.addEventListener('dragover', this._handleDragOver.bind(this));
-      button.addEventListener('dragenter', this._handleDragEnter.bind(this));
-      button.addEventListener('dragend', this._handleDragEnd.bind(this));
-      this.sidebarElement.appendChild(button);
-    }
-    const addButton = document.getElementById('zen-sidebar-add-panel-button');
-    if (data.index.length < this.MAX_SIDEBAR_PANELS) {
-      addButton.removeAttribute('hidden');
-    } else {
-      addButton.setAttribute('hidden', 'true');
-    }
-  }
-
-  async _openAddPanelDialog() {
-    let dialogURL = 'chrome://browser/content/places/zenNewWebPanel.xhtml';
-    let features = 'centerscreen,chrome,modal,resizable=no';
-    let aParentWindow = Services.wm.getMostRecentWindow('navigator:browser');
-
-    if (aParentWindow?.gDialogBox) {
-      await aParentWindow.gDialogBox.open(dialogURL, {});
-    } else {
-      aParentWindow.openDialog(dialogURL, '', features, {});
-    }
-  }
-
-  _setPinnedToElements() {
-    let sidebar = document.getElementById('zen-sidebar-web-panel');
-    sidebar.setAttribute('pinned', 'true');
-    document.getElementById('zen-sidebar-web-panel-pinned').setAttribute('pinned', 'true');
-  }
-
-  _removePinnedFromElements() {
-    let sidebar = document.getElementById('zen-sidebar-web-panel');
-    sidebar.removeAttribute('pinned');
-    document.getElementById('zen-sidebar-web-panel-pinned').removeAttribute('pinned');
-  }
-
-  _closeSidebarPanel() {
-    let sidebar = document.getElementById('zen-sidebar-web-panel');
-    sidebar.setAttribute('hidden', 'true');
-    this._lastOpenedPanel = this._currentPanel;
-    this._currentPanel = null;
-  }
-
-  _handleClick(event) {
-    let target = event.target;
-    let panelId = target.getAttribute('zen-sidebar-id');
-    if (this._currentPanel === panelId) {
-      return;
-    }
-    this._currentPanel = panelId;
-    this._updateWebPanel();
-  }
-
-  _handleDragStart(event) {
-    this.__dragingElement = event.target;
-    this.__dragingIndex = Array.prototype.indexOf.call(event.target.parentNode.children, event.target);
-    event.target.style.opacity = '0.7';
-
-    event.dataTransfer.effectAllowed = 'move';
-    event.dataTransfer.setData('text/html', event.target.innerHTML);
-    event.dataTransfer.setData('text/plain', event.target.id);
-  }
-
-  _handleDragOver(event) {}
-
-  _handleDragEnter(event) {
-    if (typeof this.__dragingElement === 'undefined') {
-      return;
-    }
-    const target = event.target;
-    const elIndex = Array.prototype.indexOf.call(target.parentNode.children, target);
-    if (elIndex < this.__dragingIndex) {
-      target.before(this.__dragingElement);
-      this.__dragingIndex = elIndex - 1;
-    }
-    target.after(this.__dragingElement);
-    this.__dragingIndex = elIndex + 1;
-  }
-
-  _handleDragEnd(event) {
-    event.target.style.opacity = '1';
-
-    let data = this.sidebarData;
-    let newPos = [];
-    for (let element of this.__dragingElement.parentNode.children) {
-      let panelId = element.getAttribute('zen-sidebar-id');
-      newPos.push(panelId);
-    }
-    data.index = newPos;
-    Services.prefs.setStringPref('zen.sidebar.data', JSON.stringify(data));
-    this._currentPanel = this.__dragingElement.getAttribute('zen-sidebar-id');
-    this.open();
-    this.__dragingElement = undefined;
-  }
-
-  _createNewPanel(url) {
-    let data = this.sidebarData;
-    let newName = 'p' + new Date().getTime();
-    data.index.push(newName);
-    data.data[newName] = {
-      url: url,
-      ua: false,
-    };
-    Services.prefs.setStringPref('zen.sidebar.data', JSON.stringify(data));
-    this._currentPanel = newName;
-    this.open();
-  }
-
-  _updateButtons() {
-    for (let button of this.sidebarElement.querySelectorAll('.zen-sidebar-panel-button')) {
-      if (button.getAttribute('zen-sidebar-id') === this._currentPanel) {
-        button.setAttribute('selected', 'true');
-      } else {
-        button.removeAttribute('selected');
-      }
-    }
-  }
-
-  _hideAllWebPanels() {
-    let sidebar = document.getElementById('zen-sidebar-web-panel');
-    for (let browser of sidebar.querySelectorAll('browser[zen-sidebar-id]')) {
-      browser.setAttribute('hidden', 'true');
-      browser.docShellIsActive = false;
-      browser.zenModeActive = false;
-    }
-  }
-
-  get introductionPanel() {
-    return document.getElementById('zen-sidebar-introduction-panel');
-  }
-
-  _updateWebPanel() {
-    this._updateButtons();
-    // let sidebar = document.getElementById("zen-sidebar-web-panel");
-    this._hideAllWebPanels();
-    if (!this._currentPanel) {
-      this.introductionPanel.removeAttribute('hidden');
-      this.forwardButton.setAttribute('disabled', true);
-      this.backButton.setAttribute('disabled', true);
-      return;
-    }
-    this.introductionPanel.setAttribute('hidden', 'true');
-    let existantWebview = this._getCurrentBrowser();
-    if (existantWebview) {
-      existantWebview.docShellIsActive = true;
-      existantWebview.zenModeActive = true;
-      existantWebview.removeAttribute('hidden');
-      document.getElementById('zen-sidebar-web-panel-title').textContent = existantWebview.contentTitle;
-      return;
-    }
-    let data = this._getWebPanelData(this._currentPanel);
-    let browser = this._createWebPanelBrowser(data);
-    let browserContainers = document.getElementById('zen-sidebar-web-panel-browser-containers');
-    browserContainers.appendChild(browser);
-    browser.addProgressListener(this.progressListener, Ci.nsIWebProgress.NOTIFY_LOCATION);
-    if (data.ua) {
-      browser.browsingContext.customUserAgent = this.DEFAULT_MOBILE_USER_AGENT;
-      browser.reload();
-    }
-    browser.docShellIsActive = true;
-    browser.zenModeActive = true;
-  }
-
-  _getWebPanelData(id) {
-    let data = this.sidebarData;
-    let panel = data.data[id];
-    if (!panel || !panel.url) {
-      return {};
-    }
-    return {
-      id: id,
-      ...panel,
-    };
-  }
-
-  getTabForBrowser(browser) {
-    return this._tabBrowserSet.get(browser);
-  }
-
-  setTabForBrowser(browser, tab) {
-    this._tabBrowserSet.set(browser, tab);
-  }
-
-  removeTabForBrowser(browser) {
-    this._tabBrowserSet.delete(browser);
-  }
-
-  _createWebPanelBrowser(data) {
-    const titleContainer = document.getElementById('zen-sidebar-web-panel-title');
-    titleContainer.textContent = 'Loading...';
-    let browser = gBrowser.createBrowser({
-      userContextId: data.userContextId,
-    });
-    const tab = this.sidebar.querySelector(`[zen-sidebar-id='${data.id}']`);
-    this.setTabForBrowser(browser, tab);
-    tab.linkedBrowser = browser;
-    tab.permanentKey = browser.permanentKey;
-    browser.setAttribute('disablefullscreen', 'true');
-    browser.setAttribute('src', data.url);
-    browser.setAttribute('zen-sidebar-id', data.id);
-    browser.addEventListener(
-      'pagetitlechanged',
-      function (event) {
-        let browser = event.target;
-        let title = browser.contentTitle;
-        if (!title) {
-          return;
-        }
-        let id = browser.getAttribute('zen-sidebar-id');
-        if (id === this._currentPanel) {
-          titleContainer.textContent = title;
-        }
-      }.bind(this)
-    );
-    return browser;
-  }
-
-  _getWebPanelIcon(url, element) {
-    let { preferredURI } = Services.uriFixup.getFixupURIInfo(url);
-    element.setAttribute('image', `page-icon:${preferredURI.spec}`);
-    if (Services.prefs.getBoolPref('zen.sidebar.use-google-favicons')) {
-      fetch(`https://s2.googleusercontent.com/s2/favicons?domain_url=${preferredURI.spec}`).then(async (response) => {
-        if (response.ok) {
-          let blob = await response.blob();
-          let reader = new FileReader();
-          reader.onload = function () {
-            element.setAttribute('image', reader.result);
-          };
-          reader.readAsDataURL(blob);
-        }
-      });
-    }
-  }
-
-  _getBrowserById(id) {
-    let sidebar = document.getElementById('zen-sidebar-web-panel');
-    return sidebar.querySelector(`browser[zen-sidebar-id="${id}"]`);
-  }
-
-  _getCurrentBrowser() {
-    return this._getBrowserById(this._currentPanel);
-  }
-
-  reload() {
-    let browser = this._getCurrentBrowser();
-    if (browser) {
-      browser.reload();
-    }
-  }
-
-  forward() {
-    let browser = this._getCurrentBrowser();
-    if (browser) {
-      browser.goForward();
-    }
-  }
-
-  back() {
-    let browser = this._getCurrentBrowser();
-    if (browser) {
-      browser.goBack();
-    }
-  }
-
-  home() {
-    let browser = this._getCurrentBrowser();
-    if (browser) {
-      browser.gotoIndex();
-    }
-  }
-
-  close() {
-    this._hideAllWebPanels();
-    this._closeSidebarPanel();
-    this._updateSidebarButton();
-  }
-
-  togglePinned(elem) {
-    if (this.sidebar.hasAttribute('pinned')) {
-      this._removePinnedFromElements();
-    } else {
-      this._setPinnedToElements();
-    }
-    this.update();
-  }
-
-  get sidebarElement() {
-    if (!this._sidebarElement) {
-      this._sidebarElement = document.getElementById('zen-sidebar-panels-sites');
-    }
-    return this._sidebarElement;
-  }
-
-  get splitterElement() {
-    if (!this._splitterElement) {
-      this._splitterElement = document.getElementById('zen-sidebar-web-panel-splitter');
-    }
-    return this._splitterElement;
-  }
-
-  get hSplitterElement() {
-    if (!this._hSplitterElement) {
-      this._hSplitterElement = document.getElementById('zen-sidebar-web-panel-hsplitter');
-    }
-    return this._hSplitterElement;
-  }
-
-  get sidebarHeader() {
-    if (!this._sidebarHeader) {
-      this._sidebarHeader = document.getElementById('zen-sidebar-web-header');
-    }
-    return this._sidebarHeader;
-  }
-
-  get sidebarWrapper() {
-    if (!this._sideBarWrapper) {
-      this._sideBarWrapper = document.getElementById('zen-sidebar-web-panel-wrapper');
-    }
-    return this._sideBarWrapper;
-  }
-
-  get sidebarHeaderButtons() {
-    if (!this._sidebarHeaderButtons) {
-      this._sidebarHeaderButtons = [...this.sidebarHeader.querySelectorAll('.toolbarbutton-1')];
-    }
-    return this._sidebarHeaderButtons;
-  }
-
-  // Context menu
-
-  updateContextMenu(aPopupMenu) {
-    let panel =
-      aPopupMenu.triggerNode && (aPopupMenu.triggerNode || aPopupMenu.triggerNode.closest('toolbarbutton[zen-sidebar-id]'));
-    if (!panel) {
-      return;
-    }
-    let id = panel.getAttribute('zen-sidebar-id');
-    this.contextTab = id;
-    let data = this._getWebPanelData(id);
-    let browser = this._getBrowserById(id);
-    let isMuted = browser && browser.audioMuted;
-    let mutedContextItem = document.getElementById('context_zenToggleMuteWebPanel');
-    document.l10n.setAttributes(
-      mutedContextItem,
-      !isMuted ? 'zen-web-side-panel-context-mute-panel' : 'zen-web-side-panel-context-unmute-panel'
-    );
-    if (!isMuted) {
-      mutedContextItem.setAttribute('muted', 'true');
-    } else {
-      mutedContextItem.removeAttribute('muted');
-    }
-    document.l10n.setAttributes(
-      document.getElementById('context_zenToogleUAWebPanel'),
-      data.ua ? 'zen-web-side-panel-context-disable-ua' : 'zen-web-side-panel-context-enable-ua'
-    );
-    if (!browser) {
-      document.getElementById('context_zenUnloadWebPanel').setAttribute('disabled', 'true');
-    } else {
-      document.getElementById('context_zenUnloadWebPanel').removeAttribute('disabled');
-    }
-  }
-
-  createContainerTabMenu(event) {
-    let window = event.target.ownerGlobal;
-    let data = this.sidebarData;
-    let panelData = data.data[this.contextTab];
-    return window.createUserContextMenu(event, {
-      isContextMenu: true,
-      excludeUserContextId: panelData.userContextId,
-      showDefaultTab: true,
-    });
-  }
-
-  contextChangeContainerTab(event) {
-    let data = this.sidebarData;
-    let userContextId = parseInt(event.target.getAttribute('data-usercontextid'));
-    data.data[this.contextTab].userContextId = userContextId;
-    Services.prefs.setStringPref('zen.sidebar.data', JSON.stringify(data));
-    let browser = this._getBrowserById(this.contextTab);
-    if (browser) {
-      browser.remove();
-      // We need to re-apply a new browser so it takes the new userContextId
-      this._updateWebPanel();
-    }
-  }
-
-  contextOpenNewTab() {
-    let browser = this._getBrowserById(this.contextTab);
-    let data = this.sidebarData;
-    let panel = data.data[this.contextTab];
-    let url = browser == null ? panel.url : browser.currentURI.spec;
-    gZenUIManager.openAndChangeToTab(url);
-    this.close();
-  }
-
-  contextToggleMuteAudio() {
-    let browser = this._getBrowserById(this.contextTab);
-    if (browser.audioMuted) {
-      browser.unmute();
-    } else {
-      browser.mute();
-    }
-  }
-
-  contextToggleUserAgent() {
-    let browser = this._getBrowserById(this.contextTab);
-    browser.browsingContext.customUserAgent = browser.browsingContext.customUserAgent ? null : this.DEFAULT_MOBILE_USER_AGENT;
-    let data = this.sidebarData;
-    data.data[this.contextTab].ua = !data.data[this.contextTab].ua;
-    Services.prefs.setStringPref('zen.sidebar.data', JSON.stringify(data));
-    browser.reload();
-  }
-
-  contextDelete() {
-    let data = this.sidebarData;
-    delete data.data[this.contextTab];
-    data.index = data.index.filter((id) => id !== this.contextTab);
-    let browser = this._getBrowserById(this.contextTab);
-    if (browser) {
-      browser.remove();
-      document.getElementById('zen-sidebar-web-panel-title').textContent = '';
-    }
-    this._currentPanel = null;
-    this._lastOpenedPanel = null;
-    this.update();
-    Services.prefs.setStringPref('zen.sidebar.data', JSON.stringify(data));
-  }
-
-  contextUnload() {
-    let browser = this._getBrowserById(this.contextTab);
-    this.removeTabForBrowser(browser);
-    browser.remove();
-    document.getElementById('zen-sidebar-web-panel-title').textContent = '';
-    this._closeSidebarPanel();
-    this.close();
-    this._lastOpenedPanel = null;
-  }
-
-  insertIntoContextMenu() {
-    const sibling = document.getElementById('context-stripOnShareLink');
-    const menuitem = document.createXULElement('menuitem');
-    menuitem.setAttribute('id', 'context-zenAddToWebPanel');
-    menuitem.setAttribute('hidden', 'true');
-    menuitem.setAttribute('oncommand', 'gZenBrowserManagerSidebar.addPanelFromContextMenu();');
-    menuitem.setAttribute('data-l10n-id', 'zen-web-side-panel-context-add-to-panel');
-    sibling.insertAdjacentElement('afterend', menuitem);
-  }
-
-  addPanelFromContextMenu() {
-    const url = gContextMenu.linkURL || gContextMenu.target.ownerDocument.location.href;
-    this._createNewPanel(url);
-  }
-}
-
-window.gZenBrowserManagerSidebar = new ZenBrowserManagerSidebar();
diff --git a/src/browser/base/zen-components/ZenTabUnloader.mjs b/src/browser/base/zen-components/ZenTabUnloader.mjs
index cf3015532..768bd4e04 100644
--- a/src/browser/base/zen-components/ZenTabUnloader.mjs
+++ b/src/browser/base/zen-components/ZenTabUnloader.mjs
@@ -202,15 +202,15 @@
         <menuseparator/>
         <menuitem id="context_zenUnloadTab"
                   data-lazy-l10n-id="tab-zen-unload"
-                  oncommand="gZenTabUnloader.unloadTab();"/>
+                  command="cmd_zenUnloadTab"/>
         <menu data-lazy-l10n-id="zen-tabs-unloader-tab-actions" id="context_zenTabActions">
           <menupopup>
             <menuitem id="context_zenPreventUnloadTab"
                       data-lazy-l10n-id="tab-zen-prevent-unload"
-                      oncommand="gZenTabUnloader.preventUnloadTab();"/>
+                      command="cmd_zenPreventUnloadTab"/>
             <menuitem id="context_zenIgnoreUnloadTab"
                       data-lazy-l10n-id="tab-zen-ignore-unload"
-                      oncommand="gZenTabUnloader.ignoreUnloadTab();"/>
+                      command="cmd_zenIgnoreUnloadTab"/>
           </menupopup>
         </menu>
       `);
diff --git a/src/browser/base/zen-components/ZenViewSplitter.mjs b/src/browser/base/zen-components/ZenViewSplitter.mjs
index c8951caec..d6e9e8fe7 100644
--- a/src/browser/base/zen-components/ZenViewSplitter.mjs
+++ b/src/browser/base/zen-components/ZenViewSplitter.mjs
@@ -63,7 +63,6 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
   currentView = -1;
   _data = [];
   _tabBrowserPanel = null;
-  __modifierElement = null;
   __hasSetMenuListener = false;
   overlay = null;
   _splitNodeToSplitters = new Map();
@@ -89,7 +88,6 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
     window.addEventListener('TabClose', this.handleTabClose.bind(this));
     window.addEventListener('TabSelect', this.onTabSelect.bind(this));
     this.initializeContextMenu();
-    this.insertPageActionButton();
     this.insertIntoContextMenu();
 
     // Add drag over listener to the browser view
@@ -105,7 +103,7 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
     const menuitem = document.createXULElement('menuitem');
     menuitem.setAttribute('id', 'context-zenSplitLink');
     menuitem.setAttribute('hidden', 'true');
-    menuitem.setAttribute('oncommand', 'gZenViewSplitter.splitLinkInNewTab();');
+    menuitem.setAttribute('command', 'cmd_zenSplitViewLinkInNewTab');
     menuitem.setAttribute('data-l10n-id', 'zen-split-link');
     sibling.insertAdjacentElement('beforebegin', menuitem);
   }
@@ -835,23 +833,6 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
     this.insetUpdateContextMenuItems();
   }
 
-  /**
-   * Insert Page Action button
-   */
-  insertPageActionButton() {
-    const element = window.MozXULElement.parseXULToFragment(`
-      <hbox id="zen-split-views-box"
-          hidden="true"
-          role="button"
-          class="urlbar-page-action"
-          onclick="gZenViewSplitter.openSplitViewPanel(event);">
-        <image id="zen-split-views-button"
-              class="urlbar-icon"/>
-      </hbox>
-    `);
-    document.getElementById('star-button-box').after(element);
-  }
-
   /**
    * Gets the tab browser panel.
    *
@@ -1400,42 +1381,6 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
     }
   }
 
-  /**
-   * Gets the modifier element.
-   *
-   * @returns {Element} The modifier element.
-   */
-  get modifierElement() {
-    if (!this.__modifierElement) {
-      const wrapper = document.getElementById('template-zen-split-view-modifier');
-      const panel = wrapper.content.firstElementChild;
-      wrapper.replaceWith(wrapper.content);
-      this.__modifierElement = panel;
-    }
-    return this.__modifierElement;
-  }
-
-  /**
-   * Opens the split view panel.
-   *
-   * @param {Event} event - The event that triggered the panel opening.
-   */
-  async openSplitViewPanel(event) {
-    const panel = this.modifierElement;
-    const target = event.target.parentNode;
-    this.updatePanelUI(panel);
-
-    if (!this.__hasSetMenuListener) {
-      this.setupPanelListeners(panel);
-      this.__hasSetMenuListener = true;
-    }
-
-    window.PanelMultiView.openPopup(panel, target, {
-      position: 'bottomright topright',
-      triggerEvent: event,
-    }).catch(console.error);
-  }
-
   /**
    * Updates the UI of the panel.
    *
@@ -1451,34 +1396,6 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
     }
   }
 
-  /**
-   * @description sets up the listeners for the panel.
-   * @param {Element} panel - The panel element
-   */
-  setupPanelListeners(panel) {
-    for (const gridType of ['hsep', 'vsep', 'grid', 'unsplit']) {
-      const selector = panel.querySelector(`.zen-split-view-modifier-preview.${gridType}`);
-      selector.addEventListener('click', () => this.handlePanelSelection(gridType, panel));
-    }
-  }
-
-  /**
-   * @description handles the panel selection.
-   * @param {string} gridType - The grid type
-   * @param {Element} panel - The panel element
-   */
-  handlePanelSelection(gridType, panel) {
-    if (gridType === 'unsplit') {
-      this.unsplitCurrentView();
-    } else {
-      const group = this._data[this.currentView];
-      group.gridType = gridType;
-      group.layoutTree = this.calculateLayoutTree(group.tabs, gridType);
-      this.activateSplitView(group, true);
-    }
-    panel.hidePopup();
-  }
-
   /**
    * @description unsplit the current view.]
    */
diff --git a/src/browser/base/zen-components/ZenWorkspaces.mjs b/src/browser/base/zen-components/ZenWorkspaces.mjs
index 6b2227a79..70f602b5e 100644
--- a/src/browser/base/zen-components/ZenWorkspaces.mjs
+++ b/src/browser/base/zen-components/ZenWorkspaces.mjs
@@ -2199,7 +2199,7 @@ var ZenWorkspaces = new (class extends ZenMultiWindowFeature {
 
     const menuPopup = document.createXULElement('menupopup');
     menuPopup.setAttribute('id', 'context-zen-change-workspace-tab-menu-popup');
-    menuPopup.setAttribute('oncommand', "ZenWorkspaces.changeTabWorkspace(event.target.getAttribute('zen-workspace-id'))");
+    menuPopup.setAttribute('command', 'cmd_zenChangeWorkspaceTab');
 
     menu.appendChild(menuPopup);
 
diff --git a/src/browser/components/places/content/zenNewWebPanel.js b/src/browser/components/places/content/zenNewWebPanel.js
deleted file mode 100644
index 6b7374ff6..000000000
--- a/src/browser/components/places/content/zenNewWebPanel.js
+++ /dev/null
@@ -1,62 +0,0 @@
-// 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/.
-
-var gZenNewWebPanel = {
-  init: function () {
-    document.addEventListener('dialogaccept', this.handleDialogAccept.bind(this));
-  },
-
-  handleURLChange: async function (aURL) {
-    try {
-      let url = new URL(aURL.value);
-    } catch (_) {
-      // TODO: Show error message
-      return;
-    }
-  },
-
-  addHttpIfMissing(url) {
-    // List of schemes to avoid
-    const avoidSchemes = ['about:', 'chrome:', 'moz-extension:', 'view-source:'];
-    // Check if the URL starts with any of the avoid schemes
-    for (let scheme of avoidSchemes) {
-      if (url.startsWith(scheme)) {
-        return url;
-      }
-    }
-    if (!url.startsWith('http://') && !url.startsWith('https://')) {
-      return 'https://' + url;
-    }
-    return url;
-  },
-
-  handleDialogAccept: async function (aEvent) {
-    document.commandDispatcher.focusedElement?.blur();
-    let url = document.getElementById('zenNWP_url');
-    let ua = document.getElementById('zenNWP_userAgent'); // checbkox
-    if (!url || !ua) {
-      return;
-    }
-    let urlValue = url.value;
-    try {
-      new URL(urlValue);
-    } catch (_) {
-      urlValue = this.addHttpIfMissing(url.value);
-    }
-    if (!url.value) {
-      return;
-    }
-    let newSite = {
-      url: urlValue,
-      ua: ua.checked,
-    };
-    let currentData = JSON.parse(Services.prefs.getStringPref('zen.sidebar.data'));
-    let newName = 'p' + new Date().getTime();
-    currentData.index.push(newName);
-    currentData.data[newName] = newSite;
-    Services.prefs.setStringPref('zen.sidebar.data', JSON.stringify(currentData));
-  },
-};
-
-gZenNewWebPanel.init();
diff --git a/src/browser/components/places/content/zenNewWebPanel.xhtml b/src/browser/components/places/content/zenNewWebPanel.xhtml
deleted file mode 100644
index 4187bb8c7..000000000
--- a/src/browser/components/places/content/zenNewWebPanel.xhtml
+++ /dev/null
@@ -1,44 +0,0 @@
-<?xml version="1.0"?>
-
-<!-- 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/. -->
-
-<!DOCTYPE window>
-
-<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
-        xmlns:html="http://www.w3.org/1999/xhtml"
-        id="zenNewWebPanel"
-        headerparent="zenNewWebPanelDialog"
-        style="min-width: 40em;">
-<dialog id="zenNewWebPanelDialog"
-        buttons="accept, cancel">
-
-  <linkset>
-    <html:link rel="stylesheet" href="chrome://global/skin/global.css" />
-    <html:link
-      rel="stylesheet"
-      href="chrome://global/content/commonDialog.css"
-    />
-    <html:link rel="stylesheet" href="chrome://global/skin/commonDialog.css" />
-
-    <html:link rel="localization" href="browser/zenNewWebPanel.ftl"/>
-    <script src="chrome://browser/content/zenThemeModifier.js"></script>
-  </linkset>
-
-  <script src="chrome://browser/content/places/zenNewWebPanel.js"/>
-
-  <label data-l10n-id="zen-new-web-panel-url"
-    control="zenNWP_url"/>
-  <html:input id="zenNWP_url"
-        type="url" onchange="gZenNewWebPanel.handleURLChange(this);"/>
-
-  <hbox flex="1" style="margin: 10px 5px;">
-    <html:input id="zenNWP_userAgent"
-          type="checkbox"/>
-    <label data-l10n-id="zen-new-web-panel-user-agent"
-      control="zenNWP_userAgent" for="zenNWP_userAgent"/>
-  </hbox>
-
-</dialog>
-</window>
diff --git a/src/browser/components/places/jar-mn.patch b/src/browser/components/places/jar-mn.patch
deleted file mode 100644
index 446ce0cd4..000000000
--- a/src/browser/components/places/jar-mn.patch
+++ /dev/null
@@ -1,10 +0,0 @@
-diff --git a/browser/components/places/jar.mn b/browser/components/places/jar.mn
-index e12c6bbf449f062fd22ef260909b539857f52c6a..2dcc143109de015e4c9d486b83119ae1122d2e71 100644
---- a/browser/components/places/jar.mn
-+++ b/browser/components/places/jar.mn
-@@ -25,3 +25,5 @@ browser.jar:
-     content/browser/places/interactionsViewer.css        (metadataViewer/interactionsViewer.css)
-     content/browser/places/interactionsViewer.html       (metadataViewer/interactionsViewer.html)
-     content/browser/places/interactionsViewer.js         (metadataViewer/interactionsViewer.js)
-+    content/browser/places/zenNewWebPanel.xhtml      (content/zenNewWebPanel.xhtml)
-+    content/browser/places/zenNewWebPanel.js         (content/zenNewWebPanel.js)
diff --git a/src/browser/components/preferences/zen-settings.js b/src/browser/components/preferences/zen-settings.js
index ad1903850..e8d32f43a 100644
--- a/src/browser/components/preferences/zen-settings.js
+++ b/src/browser/components/preferences/zen-settings.js
@@ -919,16 +919,6 @@ var gZenCKSSettings = {
 };
 
 Preferences.addAll([
-  {
-    id: 'zen.sidebar.enabled',
-    type: 'bool',
-    default: true,
-  },
-  {
-    id: 'zen.sidebar.close-on-blur',
-    type: 'bool',
-    default: true,
-  },
   {
     id: 'zen.view.compact.hide-toolbar',
     type: 'bool',
diff --git a/src/browser/components/preferences/zenLooksAndFeel.inc.xhtml b/src/browser/components/preferences/zenLooksAndFeel.inc.xhtml
index e9f5fe73a..59fc7dcf9 100644
--- a/src/browser/components/preferences/zenLooksAndFeel.inc.xhtml
+++ b/src/browser/components/preferences/zenLooksAndFeel.inc.xhtml
@@ -134,27 +134,6 @@
       </vbox>
 </groupbox>
 
-<hbox id="zenSidePanelsCategory"
-      class="subcategory"
-      hidden="true"
-      data-category="paneZenLooks">
-<html:h1 data-l10n-id="pane-zen-side-panels-title"/>
-</hbox>
-
-<groupbox id="zenSidePanelsGroup" data-category="paneZenLooks" hidden="true" class="highlighting-group">
-      <label><html:h2 data-l10n-id="zen-side-panels-header"/></label>
-      <description class="description-deemphasized" data-l10n-id="zen-side-panels-description" />
-
-      <checkbox id="zenLooksAndFeelUseThemedToolbar"
-            data-l10n-id="zen-side-panels-enabled"
-            preference="zen.sidebar.enabled"/>
-      <hbox class="indent">
-            <checkbox id="zenLooksAndFeelSidebarCloseOnBlur"
-                  data-l10n-id="zen-side-panels-close-on-blur"
-                  preference="zen.sidebar.close-on-blur"/>
-      </hbox>
-</groupbox>
-
 <hbox id="zenGlanceCategory"
       class="subcategory"
       hidden="true"
diff --git a/src/browser/components/preferences/zenTabsManagement.inc.xhtml b/src/browser/components/preferences/zenTabsManagement.inc.xhtml
index 47236d364..ed1ef4432 100644
--- a/src/browser/components/preferences/zenTabsManagement.inc.xhtml
+++ b/src/browser/components/preferences/zenTabsManagement.inc.xhtml
@@ -6,7 +6,7 @@
 <html:h1 data-l10n-id="pane-workspaces-title"/>
 </hbox>
 
-<hbox id="zenSidePanelsCategory"
+<hbox id="zenTabManagementCategory"
       class="subcategory"
       hidden="true"
       data-category="paneZenTabManagement">
diff --git a/src/browser/themes/shared/zen-icons/icons.css b/src/browser/themes/shared/zen-icons/icons.css
index cf000af85..74bb5d11d 100644
--- a/src/browser/themes/shared/zen-icons/icons.css
+++ b/src/browser/themes/shared/zen-icons/icons.css
@@ -82,10 +82,6 @@
   list-style-image: url('chrome://browser/skin/sidebars.svg') !important;
 }
 
-#zen-sidepanel-button {
-  list-style-image: url('sidebar.svg');
-}
-
 #downloads-button,
 #downloads-indicator-anchor,
 #appMenu-downloads-button,
diff --git a/src/browser/themes/shared/zen-icons/lin/icons.css b/src/browser/themes/shared/zen-icons/lin/icons.css
index e492aa771..d52a1e7fe 100644
--- a/src/browser/themes/shared/zen-icons/lin/icons.css
+++ b/src/browser/themes/shared/zen-icons/lin/icons.css
@@ -72,10 +72,6 @@
   list-style-image: url('chrome://browser/skin/sidebars.svg') !important;
 }
 
-#zen-sidepanel-button {
-  list-style-image: url('sidebar.svg');
-}
-
 #downloads-button,
 #downloads-indicator-anchor,
 #appMenu-downloads-button,
diff --git a/src/toolkit/components/pictureinpicture/PictureInPicture-sys-mjs.patch b/src/toolkit/components/pictureinpicture/PictureInPicture-sys-mjs.patch
index feaef745e..67c667969 100644
--- a/src/toolkit/components/pictureinpicture/PictureInPicture-sys-mjs.patch
+++ b/src/toolkit/components/pictureinpicture/PictureInPicture-sys-mjs.patch
@@ -1,16 +1,8 @@
 diff --git a/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs b/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
-index 5da0404b2672ba8cce7bcf808bf2373474776654..44b62bd752294c2af96dd5b5d08c90ddf3dc513f 100644
+index 5da0404b2672ba8cce7bcf808bf2373474776654..1405c53a927a64ecda8255d78d9aa5ddf8806685 100644
 --- a/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
 +++ b/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
-@@ -488,13 +488,13 @@ export var PictureInPicture = {
-       return;
-     }
- 
--    let gBrowser = browser.getTabBrowser();
--    let tab = gBrowser.getTabForBrowser(browser);
-+    let gBrowser = browser?.ownerGlobal?.gBrowser;
-+    let tab = browser?.ownerGlobal?.gZenBrowserManagerSidebar.getTabForBrowser(browser) ?? gBrowser.getTabForBrowser(browser);
- 
+@@ -494,7 +494,7 @@ export var PictureInPicture = {
      // focus the tab's window
      tab.ownerGlobal.focus();
  
@@ -27,12 +19,3 @@ index 5da0404b2672ba8cce7bcf808bf2373474776654..44b62bd752294c2af96dd5b5d08c90dd
      let browserHasPip = !!this.browserWeakMap.get(browser);
      if (browserHasPip) {
        this.setUrlbarPipIconActive(browser.ownerGlobal);
-@@ -877,7 +878,7 @@ export var PictureInPicture = {
-     win.setIsMutedState(videoData.isMuted);
- 
-     // set attribute which shows pip icon in tab
--    let tab = parentWin.gBrowser.getTabForBrowser(browser);
-+    let tab = parentWin.gBrowser.getTabForBrowser(browser) ?? parentWin.gZenBrowserManagerSidebar.getTabForBrowser(browser);;
-     tab.setAttribute("pictureinpicture", true);
- 
-     this.setUrlbarPipIconActive(parentWin);