code: function () {
  
              var oMask = this.mask,
                  oParentNode;
  
              if (oMask) {
                  /*
                      Hide the mask before destroying it to ensure that DOM
                      event handlers on focusable elements get removed.
                  */
                  this.hideMask();
  
                  oParentNode = oMask.parentNode;
                  if (oParentNode) {
                      oParentNode.removeChild(oMask);
                  }
  
                  this.mask = null;
              }
          }
docs: Removes the modality mask.
  @method removeMask