gh-11766: Fixed video fullscreen not working while in glance (gh-14272)

Co-authored-by: mr. m <91018726+mr-cheffy@users.noreply.github.com>
Signed-off-by: mr. m <91018726+mr-cheffy@users.noreply.github.com>

src/zen/glance/ZenGlanceManager.mjs

@@ -53,6 +53,10 @@ class nsZenGlanceManager extends nsZenDOMOperatedFeature {
   #setupEventListeners() {
     window.addEventListener("TabClose", this.onTabClose.bind(this));
     window.addEventListener("TabSelect", this.onLocationChange.bind(this));
+    window.addEventListener(
+      "MozDOMFullscreen:Entered",
+      this.onFullscreenEntered.bind(this)
+    );
 
     document
       .getElementById("tabbrowser-tabpanels")
@@ -1414,6 +1418,23 @@ class nsZenGlanceManager extends nsZenDOMOperatedFeature {
     }
   }
 
+  /**
+   * Handle DOM Fullscreen request while inside glance
+   *
+   * @param {Event} event - The MozDOMFullscreen:Entered event
+   */
+  onFullscreenEntered(event) {
+    const browser = this.#currentBrowser;
+
+    if (!browser) {
+      return;
+    }
+
+    if (event.target === browser) {
+      this.fullyOpenGlance();
+    }
+  }
+
   /**
    * Manage tab close for glance tabs
    *