From 014eabed3cbdbfd0a4cf07c75d22d0c84cb6f130 Mon Sep 17 00:00:00 2001
From: "mr. m" <91018726+mr-cheffy@users.noreply.github.com>
Date: Tue, 21 Apr 2026 01:18:48 +0200
Subject: [PATCH] no-bug: Fixed loading bar appearing twice (gh-13337)

---
 prefs/zen/glance.yaml                          |  2 +-
 src/zen/common/sys/ui/ZenProgressBar.sys.mjs   | 17 ++++++++++++++---
 src/zen/sessionstore/ZenSessionManager.sys.mjs | 11 +++++++----
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/prefs/zen/glance.yaml b/prefs/zen/glance.yaml
index cf73cddb9..5788dbca1 100644
--- a/prefs/zen/glance.yaml
+++ b/prefs/zen/glance.yaml
@@ -15,7 +15,7 @@
   value: "alt" # ctrl, alt, shift
 
 - name: zen.glance.animation-duration
-  value: 300 # in milliseconds
+  value: 350 # in milliseconds
 
 - name: zen.glance.deactivate-docshell-during-animation
   value: false
diff --git a/src/zen/common/sys/ui/ZenProgressBar.sys.mjs b/src/zen/common/sys/ui/ZenProgressBar.sys.mjs
index d1add0fc6..511c68c37 100644
--- a/src/zen/common/sys/ui/ZenProgressBar.sys.mjs
+++ b/src/zen/common/sys/ui/ZenProgressBar.sys.mjs
@@ -10,6 +10,7 @@ export class ZenProgressBar extends ZenUIComponent {
   #element = null;
   #loadingTab = null;
   #longLoadTimer = null;
+  #promise = null;
 
   init() {
     this.listenBrowserTabsProgress();
@@ -60,7 +61,8 @@ export class ZenProgressBar extends ZenUIComponent {
     return this.#element;
   }
 
-  #checkBrowserProgress(webProgress) {
+  async #checkBrowserProgress(webProgress) {
+    await this.#promise;
     const window = this.window;
     const gBrowser = window.gBrowser;
     const tab = gBrowser.getTabForBrowser(webProgress);
@@ -74,7 +76,7 @@ export class ZenProgressBar extends ZenUIComponent {
     }
   }
 
-  #hideProgressBar() {
+  #hideProgressBar(aInstant = false) {
     const progressBar = this.#element;
     const window = this.window;
     if (this.#longLoadTimer) {
@@ -86,12 +88,15 @@ export class ZenProgressBar extends ZenUIComponent {
     if (!progressBar) {
       return;
     }
+    let { promise, resolve } = Promise.withResolvers();
+    this.#promise = promise;
     const callback = () => {
       delete progressBar._loadingTab;
       progressBar.remove();
       this.#element = null;
+      resolve();
     };
-    if (this.window.gReduceMotion) {
+    if (this.window.gReduceMotion || aInstant) {
       callback();
       return;
     }
@@ -113,6 +118,11 @@ export class ZenProgressBar extends ZenUIComponent {
     if (this.#loadingTab === aTab) {
       return;
     }
+    if (this.#element) {
+      return;
+    }
+    let { promise, resolve } = Promise.withResolvers();
+    this.#promise = promise;
     this.#loadingTab = aTab;
     const progressBar = this.#progressBar;
     progressBar.removeAttribute("fade-out");
@@ -123,5 +133,6 @@ export class ZenProgressBar extends ZenUIComponent {
       }
       this.#longLoadTimer = null;
     }, WAIT_BEFORE_SHOWING_LONG_LOAD);
+    resolve();
   }
 }
diff --git a/src/zen/sessionstore/ZenSessionManager.sys.mjs b/src/zen/sessionstore/ZenSessionManager.sys.mjs
index f784e1656..39f2d0eb2 100644
--- a/src/zen/sessionstore/ZenSessionManager.sys.mjs
+++ b/src/zen/sessionstore/ZenSessionManager.sys.mjs
@@ -290,10 +290,13 @@ export class nsZenSessionManager {
       console.error("ZenSessionManager: Failed to read session file", e);
     }
     this.#sidebar = this._dataFromFile || {};
-    if (!this.#sidebar.spaces?.length && !this._shouldRunMigration) {
+    if (
+      !this.#sidebarWithoutCloning.spaces?.length &&
+      !this._shouldRunMigration
+    ) {
       this.log(
         "No spaces data found in session file, running migration",
-        this.#sidebar
+        this.#sidebarWithoutCloning
       );
       // If we have no spaces data, we should run migration
       // to restore them from the database. Note we also do a
@@ -304,7 +307,7 @@ export class nsZenSessionManager {
     if (
       Services.prefs.getBoolPref("zen.session-store.log-tab-entries", false)
     ) {
-      for (const tab of this.#sidebar.tabs || []) {
+      for (const tab of this.#sidebarWithoutCloning.tabs || []) {
         this.log("Tab entry in session file:", tab);
       }
     }
@@ -492,7 +495,7 @@ export class nsZenSessionManager {
     delete this._migrationData?.recoveryData;
     // Restore spaces into the sidebar object if we don't
     // have any yet.
-    if (!this.#sidebar.spaces?.length) {
+    if (!this.#sidebarWithoutCloning.spaces?.length) {
       this.#sidebar = {
         ...this.#sidebar,
         spaces: this._migrationData?.spaces || [],