The Tor Browser / file revision

 /* Any copyright is dedicated to the Public Domain.

  * http://creativecommons.org/publicdomain/zero/1.0/

  */

 const kButtonId = "test-tabbar-size-with-large-buttons";

 function test() {

   registerCleanupFunction(cleanup);

   let titlebar = document.getElementById("titlebar");

   let originalHeight = titlebar.getBoundingClientRect().height;

   let button = document.createElement("toolbarbutton");

   button.id = kButtonId;

   button.setAttribute("style", "min-height: 100px");

   gNavToolbox.palette.appendChild(button);

   CustomizableUI.addWidgetToArea(kButtonId, CustomizableUI.AREA_TABSTRIP);

   let currentHeight = titlebar.getBoundingClientRect().height;

   ok(currentHeight > originalHeight, "Titlebar should have grown");

   CustomizableUI.removeWidgetFromArea(kButtonId);

   currentHeight = titlebar.getBoundingClientRect().height;

   is(currentHeight, originalHeight, "Titlebar should have gone back to its original size.");

 }

 function cleanup() {

   let btn = document.getElementById(kButtonId);

   if (btn) {

     btn.remove();

   }

 }