anchor.diff:    if(urlInput.value.isEmpty) {
       urlInput.value = 'http://';
     } else {
  -    refreshPreviewContent(null);
  +    onRefreshClick(null);
     }
   
     SortableGroup sg = new SortableGroup();
  
positive.code: 
  
  }
  void formBlur(MouseEvent e) {
    var target = e.target as HtmlElement;
    target.parent.querySelector('span.${e.currentTarget.className}').text = target.value;
  
  
negative.code: 
    var spans = querySelectorAll(".preview form span");
    for (HtmlElement span in spans) {
      span.onClick.listen(onDimensionLabelClick);
    }
    var inputs = querySelectorAll(".preview form input");
    for (HtmlElement input in inputs) {
      input.onBlur.listen(onDimensionInputBlur);
    }
  
  }
  
  void onDimensionLabelClick(Event e) {
    var target = (e.target as HtmlElement);
    var parent = target.parent;
    parent.querySelectorAll("span").style.display = 'none';
  