The Tor Browser / file revision

 /* Any copyright is dedicated to the Public Domain.

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

 function test() {

   let cw;

   let win;

   waitForExplicitFinish();

   newWindowWithTabView(function (tvwin) {

     win = tvwin;

     cw = win.TabView.getContentWindow();

     registerCleanupFunction(function () {

       if (win && !win.closed)

         win.close();

     });

     // fill the group item with some tabs

     for (let i = 0; i < 5; i++)

       win.gBrowser.loadOneTab("about:blank");

     let groupItem = cw.GroupItems.groupItems[0];

     groupItem.setSize(400, 400, true);

     let range = new cw.Range(1, 400);

     // determine the groupItem's largest possible stacked size

     while (range.extent > 1) {

       let pivot = Math.floor(range.extent / 2);

       groupItem.setSize(range.min + pivot, range.min + pivot, true);

       if (groupItem.isStacked())

         range.min += pivot;

       else

         range.max -= pivot;

     }

     // stack the group

     groupItem.setSize(range.min, range.min, true);

     ok(groupItem.isStacked(), "groupItem is stacked");

     // one step back to un-stack the groupItem

     groupItem.setSize(range.max, range.max, true);

     ok(!groupItem.isStacked(), "groupItem is no longer stacked");

     // check that close buttons are visible

     let tabItem = groupItem.getChild(0);

     isnot(tabItem.$close.css("display"), "none", "close button is visible");

     finish();

   });

 }