code: function () {
          var btnElm = this.getEl().firstChild,
            btnStyle;
  
          if (btnElm) {
            btnStyle = btnElm.style;
            btnStyle.width = btnStyle.height = "100%";
          }
  
          this._super();
        }
docs: Repaints the button for example after it's been resizes by a layout engine.
  
  @method repaint