diff -r 000000000000 -r 6474c204b198 browser/base/content/test/general/browser_menuButtonFitts.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/general/browser_menuButtonFitts.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,32 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+function test () {
+  waitForExplicitFinish();
+  window.maximize();
+
+  // Find where the nav-bar is vertically.
+  var navBar = document.getElementById("nav-bar");
+  var boundingRect = navBar.getBoundingClientRect();
+  var yPixel = boundingRect.top + Math.floor(boundingRect.height / 2);
+  var xPixel = boundingRect.width - 1; // Use the last pixel of the screen since it is maximized.
+
+  function onPopupHidden() {
+    PanelUI.panel.removeEventListener("popuphidden", onPopupHidden);
+    window.restore();
+    finish();
+  }
+  function onPopupShown() {
+    PanelUI.panel.removeEventListener("popupshown", onPopupShown);
+    ok(true, "Clicking at the far edge of the window opened the menu popup.");
+    PanelUI.panel.addEventListener("popuphidden", onPopupHidden);
+    PanelUI.hide();
+  }
+  registerCleanupFunction(function() {
+    PanelUI.panel.removeEventListener("popupshown", onPopupShown);
+    PanelUI.panel.removeEventListener("popuphidden", onPopupHidden);
+  });
+  PanelUI.panel.addEventListener("popupshown", onPopupShown);
+  EventUtils.synthesizeMouseAtPoint(xPixel, yPixel, {}, window);
+}