From f0cbaf511aeae6f0dae8a6f1d7a7d55cf33f2c8c Mon Sep 17 00:00:00 2001
From: Chris Pearce <chris@pearce.org.nz>
Date: Tue, 8 Nov 2011 12:58:48 +1300
Subject: [PATCH] Bug 699885 part 2 - Exit DOM full-screen if we've changed tab
 or app by the time the request is granted. r=dao

---
 browser/base/content/browser.js | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 13a8c8103a0..ae06684d7a9 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -3913,14 +3913,36 @@ var FullScreen = {
   },
 
   enterDomFullScreen : function(event) {
+    if (!document.mozFullScreen) {
+      return;
+    }
+
     // We receive "mozfullscreenchange" events for each subdocument which
     // is an ancestor of the document containing the element which requested
     // full-screen. Only add listeners and show warning etc when the event we
     // receive is targeted at the chrome document, i.e. only once every time
     // we enter DOM full-screen mode.
-    if (!document.mozFullScreen || event.target.ownerDocument != document) {
+    let targetDoc = event.target.ownerDocument ? event.target.ownerDocument : event.target;
+    if (targetDoc != document) {
+      // However, if we receive a "mozfullscreenchange" event for a document
+      // which is not a subdocument of the currently selected tab, we know that
+      // we've switched tabs since the request to enter full-screen was made,
+      // so we should exit full-screen since the "full-screen document" isn't
+      // acutally visible.
+      if (targetDoc.defaultView.top != gBrowser.contentWindow) {
+        document.mozCancelFullScreen();
+      }
       return;
     }
+
+    let focusManger = Cc["@mozilla.org/focus-manager;1"].getService(Ci.nsIFocusManager);
+    if (focusManger.activeWindow != window) {
+      // The top-level window has lost focus since the request to enter
+      // full-screen was made. Cancel full-screen.
+      document.mozCancelFullScreen();
+      return;
+    }
+
     this.showWarning(true);
 
     // Exit DOM full-screen mode upon open, close, or change tab.