code: function () {
  
              if (this.iframe) {
                  this.iframe.parentNode.removeChild(this.iframe);
              }
  
              this.iframe = null;
  
              Overlay.windowResizeEvent.unsubscribe(
                  this.doCenterOnDOMEvent, this);
      
              Overlay.windowScrollEvent.unsubscribe(
                  this.doCenterOnDOMEvent, this);
  
              Module.textResizeEvent.unsubscribe(this._autoFillOnHeightChange);
  
              if (this._contextTriggers) {
                  // Unsubscribe context triggers - to cover context triggers which listen for global
                  // events such as windowResize and windowScroll. Easier just to unsubscribe all
                  this._processTriggers(this._contextTriggers, _UNSUBSCRIBE, this._alignOnTrigger);
              }
  
              Overlay.superclass.destroy.call(this);
          }
docs: Removes the Overlay element from the DOM and sets all child
  elements to null.
  @method destroy