code: function () {
              var oUnderlay = this.underlay,
                  oElement;
  
              if (oUnderlay) {
                  oElement = this.element;
                  oUnderlay.style.width = oElement.offsetWidth + "px";
                  oUnderlay.style.height = oElement.offsetHeight + "px";
              }
          }
docs: Adjusts the size of the shadow based on the size of the element.
  @method sizeUnderlay