code: function (dw, dh) {
          var self = this, rect = self.layoutRect();
  
          return self.resizeTo(rect.w + dw, rect.h + dh);
        }
docs: Resizes the control to a specific relative width/height.
  
  @method resizeBy
  @param {Number} dw Relative control width.
  @param {Number} dh Relative control height.
  @return {tinymce.ui.Control} Current control instance.