code: function tabView_waitForGroupUndo(aSpec) {
      var spec = aSpec || {};
      var group = spec.group;
  
      if (!group) {
        throw new Error(arguments.callee.name + ": Group not specified.");
      }
  
      var element = null;
      this._groupItemsObject.groupItems.forEach(function(node) {
        if (node.container == group.getNode()) {
          element = node;
        }
      });
  
      mozmill.utils.waitFor(function() {
        return element && element.hidden == false;
      }, TIMEOUT, 100, "Tab Group has not been reopened.");
  
      // XXX: Ugly but otherwise the events on the button aren't get processed
      this._controller.sleep(0);
    }
docs: Wait until the specified tab group has been reopened
  
  @param {object} aSpec
  Information on which group to operate on
  Elements: group - Group