diff -r 000000000000 -r 6474c204b198 browser/components/customizableui/test/browser_972267_customizationchange_events.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/customizableui/test/browser_972267_customizationchange_events.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,47 @@
+/* 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";
+
+// Create a new window, then move the home button to the menu and check both windows have
+// customizationchange events fire on the toolbox:
+add_task(function() {
+  let newWindow = yield openAndLoadWindow();
+  let otherToolbox = newWindow.gNavToolbox;
+
+  let handlerCalledCount = 0;
+  let handler = (ev) => {
+    handlerCalledCount++;
+  };
+
+  let homeButton = document.getElementById("home-button");
+
+  gNavToolbox.addEventListener("customizationchange", handler);
+  otherToolbox.addEventListener("customizationchange", handler);
+
+  gCustomizeMode.addToPanel(homeButton);
+
+  is(handlerCalledCount, 2, "Should be called for both windows.");
+
+  // If the test is run in isolation and the panel has never been open,
+  // the button will be in the palette. Deal with this case:
+  if (homeButton.parentNode.id == "BrowserToolbarPalette") {
+    yield PanelUI.ensureReady();
+    isnot(homeButton.parentNode.id, "BrowserToolbarPalette", "Home button should now be in panel");
+  }
+
+  handlerCalledCount = 0;
+  gCustomizeMode.addToToolbar(homeButton);
+  is(handlerCalledCount, 2, "Should be called for both windows.");
+
+  gNavToolbox.removeEventListener("customizationchange", handler);
+  otherToolbox.removeEventListener("customizationchange", handler);
+
+  yield promiseWindowClosed(newWindow);
+});
+
+add_task(function asyncCleanup() {
+  yield resetCustomization();
+});
+