diff -r 000000000000 -r 6474c204b198 browser/components/tabview/test/browser_tabview_bug648882.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/tabview/test/browser_tabview_bug648882.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function test() {
+  waitForExplicitFinish();
+
+  newWindowWithTabView(function (win) {
+    registerCleanupFunction(function () win.close());
+
+    let cw = win.TabView.getContentWindow();
+    let tab = win.gBrowser.tabs[0];
+    let tabItem = tab._tabViewTabItem;
+    let isIdle = false;
+
+    // We replace UI.isIdle() here to not rely on setTimeout(). While this
+    // function returns false (busy) we expect no tabItem updates to happen.
+    let busyCount = 5;
+    cw.UI.isIdle = function () {
+      return isIdle = (0 > --busyCount);
+    };
+
+    cw.TabItems.pausePainting();
+
+    tabItem.addSubscriber("updated", function onUpdated() {
+      tabItem.removeSubscriber("updated", onUpdated);
+      ok(isIdle, "tabItem is updated only when UI is idle");
+      finish();
+    });
+
+    cw.TabItems.update(tab);
+    cw.TabItems.resumePainting();
+  });
+}