diff -r 000000000000 -r 6474c204b198 browser/components/tabview/test/browser_tabview_startup_transitions.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/tabview/test/browser_tabview_startup_transitions.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,59 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+var prefsBranch = Cc["@mozilla.org/preferences-service;1"].
+                  getService(Ci.nsIPrefService).
+                  getBranch("browser.panorama.");
+
+function animateZoom() prefsBranch.getBoolPref("animate_zoom");
+
+function test() {
+  waitForExplicitFinish();
+  
+  let charsetArg = "charset=" + window.content.document.characterSet;
+  let win = window.openDialog(getBrowserURL(), "_blank", "chrome,all,dialog=no",
+                              "about:blank", charsetArg, null, null, true);
+
+  registerCleanupFunction(function() {
+    prefsBranch.setBoolPref("animate_zoom", true);
+    win.close();
+  });
+
+  ok(animateZoom(), "By default, we animate on zoom.");
+  prefsBranch.setBoolPref("animate_zoom", false);
+  ok(!animateZoom(), "animate_zoom = false");
+  
+  let onLoad = function() {
+    win.removeEventListener("load", onLoad, false);
+
+    // a few shared references
+    let tabViewWindow = null;
+    let transitioned = 0;
+
+    let initCallback = function() {
+      tabViewWindow = win.TabView.getContentWindow();
+      function onTransitionEnd(event) {
+        transitioned++;
+        info(transitioned);
+      }
+      tabViewWindow.document.addEventListener("transitionend", onTransitionEnd, false);
+
+      // don't use showTabView() here because we only want to check whether 
+      // zoom out animation happens. Other animations would happen before
+      // the callback as waitForFocus() was added to showTabView() in head.js
+      let onTabViewShown = function() {
+        tabViewWindow.removeEventListener("tabviewshown", onTabViewShown, false);
+        tabViewWindow.document.removeEventListener("transitionend", onTransitionEnd, false);
+
+        ok(!transitioned, "There should be no transitions");
+
+        finish();
+      };
+      tabViewWindow.addEventListener("tabviewshown", onTabViewShown, false);
+      win.TabView.toggle();
+    };
+
+    win.TabView._initFrame(initCallback);
+  }
+  win.addEventListener("load", onLoad, false);
+}