code: function(firstElement, lastElement) {
  
              firstElement = firstElement || this.firstButton;
              lastElement = this.lastButton || lastElement;
  
              Dialog.superclass.setTabLoop.call(this, firstElement, lastElement);
          }
docs: Sets up a tab, shift-tab loop between the first and last elements
  provided. NOTE: Sets up the preventBackTab and preventTabOut KeyListener
  instance properties, which are reset everytime this method is invoked.
  
  @method setTabLoop
  @param {HTMLElement} firstElement
  @param {HTMLElement} lastElement