docs: function() {
          if (!this.imgDiv || this.isLoading) {
              return;
          }
          var backBuffer;
          if (this.frame) {
              backBuffer = this.frame.cloneNode(false);
              backBuffer.appendChild(this.imgDiv);
          } else {
              backBuffer = this.imgDiv;
          }
          this.imgDiv = null;
          return backBuffer;
      }