anchor.diff:    String text;
     int imgWidth;
   
  -  TooltipModel(String this.imgUrl, String this.text,
  -      int this.imgWidth);
  +  TooltipModel(this.imgUrl, this.text, this.imgWidth);
   }
  
positive.code: 
      tooltipElem = new dom.DivElement();
  
      dom.ImageElement imgElem = new dom.ImageElement();
      imgElem.width = displayModel.imgWidth;
      imgElem.src = displayModel.imgUrl;
      tooltipElem.append(imgElem);
  
      if (displayModel.text != null) {
        dom.DivElement textSpan = new dom.DivElement();
        textSpan.appendText(displayModel.text);
        textSpan.style.color = "white";
        textSpan.style.fontSize = "smaller";
        textSpan.style.paddingBottom = "5px";
  
        tooltipElem.append(textSpan);
      }
  
      tooltipElem.style.padding = "5px";
      tooltipElem.style.paddingBottom = "0px";
      tooltipElem.style.backgroundColor = "black";
      tooltipElem.style.borderRadius = "5px";
      tooltipElem.style.width = "${displayModel.imgWidth.toString()}px";
  
      // find the coordinates of the parent DOM element
      Rectangle bounds = element.getBoundingClientRect();
      int left = (bounds.left + dom.window.pageXOffset).toInt();
      int top = (bounds.top + dom.window.pageYOffset).toInt();
      int width = (bounds.width).toInt();
      int height = (bounds.height).toInt();
  
      // position the tooltip.
      // Figure out where the containing element sits in the window.
      int tooltipLeft = left + width + 10;
      int tooltipTop = top - height;
      tooltipElem.style.position = "absolute";
      tooltipElem.style.top = "${tooltipTop}px";
      tooltipElem.style.left = "${tooltipLeft}px";
  
      // Add the tooltip to the document body. We add it here because
      // we need to position it absolutely, without reference to its
  
negative.code: 
    dom.Element tooltipElem;
  
    Tooltip(this.element, this.node, this.scope) {
      element
        ..onMouseEnter.listen((_) => _createTemplate())
        ..onMouseLeave.listen((_) => _destroyTemplate());
    }
  
    _createTemplate() {
  