anchor.diff:  HtmlElement container;
   HtmlElement draggedElement;
   num previewCounter = 0;
  +SortableGroup sortableGroup = new SortableGroup();
   
   void main() {
     container = querySelector('#container');
  
positive.code: 
    updatePreviewSize(div);
  
    var spans = div.querySelectorAll("form span");
    for (HtmlElement span in spans) {
      span.onClick.listen(onDimensionLabelClick);
  
negative.code: 
  void onCloneButtonClick(Event e) {
    var preview = findParentPreview(e.target as HtmlElement);
    DivElement previewDiv = preview.clone(true);
    preview.parent.insertBefore(previewDiv,preview);
    registerEvents(previewDiv);
  }
  
  
  