diff -r 000000000000 -r 6474c204b198 browser/components/customizableui/test/browser_943683_migration_test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/customizableui/test/browser_943683_migration_test.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,50 @@
+/* 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";
+
+const kWidgetId = "test-addonbar-migration";
+const kWidgetId2 = "test-addonbar-migration2";
+
+let addonbar = document.getElementById(CustomizableUI.AREA_ADDONBAR);
+let navbar = document.getElementById(CustomizableUI.AREA_NAVBAR);
+
+let btn;
+let btn2;
+
+// Check we migrate normal stuff to the navbar
+add_task(function() {
+  btn = createDummyXULButton(kWidgetId, "Test");
+  btn2 = createDummyXULButton(kWidgetId2, "Test2");
+  addonbar.insertItem(btn.id);
+  ok(btn.parentNode == navbar.customizationTarget, "Button should end up in navbar");
+  let migrationArray = addonbar.getMigratedItems();
+  is(migrationArray.length, 1, "Should have migrated 1 item");
+  is(migrationArray[0], kWidgetId, "Should have migrated our 1 item");
+
+  addonbar.currentSet = addonbar.currentSet + "," + kWidgetId2;
+  ok(btn2.parentNode == navbar.customizationTarget, "Second button should end up in the navbar");
+  migrationArray = addonbar.getMigratedItems();
+  is(migrationArray.length, 2, "Should have migrated 2 items");
+  isnot(migrationArray.indexOf(kWidgetId2), -1, "Should have migrated our second item");
+
+  let otherWindow = yield openAndLoadWindow(undefined, true);
+  try {
+    let addonBar = otherWindow.document.getElementById("addon-bar");
+    let otherMigrationArray = addonBar.getMigratedItems();
+    is(migrationArray.length, otherMigrationArray.length,
+       "Other window should have the same number of migrated items.");
+    if (migrationArray.length == otherMigrationArray.length) {
+      for (let widget of migrationArray) {
+        isnot(otherMigrationArray.indexOf(widget), -1,
+              "Migrated widget " + widget + " should also be listed as migrated in the other window.");
+      }
+    }
+  } finally {
+    yield promiseWindowClosed(otherWindow);
+  }
+  btn.remove();
+  btn2.remove();
+  CustomizableUI.reset();
+});