diff -r 000000000000 -r 6474c204b198 browser/components/customizableui/test/browser_945739_showInPrivateBrowsing_customize_mode.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/customizableui/test/browser_945739_showInPrivateBrowsing_customize_mode.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,35 @@
+/* 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-private-browsing-customize-mode-widget";
+
+// Add a widget via the API with showInPrivateBrowsing set to false
+// and ensure it does not appear in the list of unused widgets in private
+// windows.
+add_task(function testPrivateBrowsingCustomizeModeWidget() {
+  CustomizableUI.createWidget({
+    id: kWidgetId,
+    showInPrivateBrowsing: false
+  });
+
+  let normalWidgetArray = CustomizableUI.getUnusedWidgets(gNavToolbox.palette);
+  normalWidgetArray = normalWidgetArray.map((w) => w.id);
+  ok(normalWidgetArray.indexOf(kWidgetId) > -1,
+     "Widget should appear as unused in non-private window");
+
+  let privateWindow = yield openAndLoadWindow({private: true});
+  let privateWidgetArray = CustomizableUI.getUnusedWidgets(privateWindow.gNavToolbox.palette);
+  privateWidgetArray = privateWidgetArray.map((w) => w.id);
+  is(privateWidgetArray.indexOf(kWidgetId), -1,
+     "Widget should not appear as unused in private window");
+  yield promiseWindowClosed(privateWindow);
+
+  CustomizableUI.destroyWidget(kWidgetId); 
+});
+
+add_task(function asyncCleanup() {
+  yield resetCustomization();
+});