anchor.diff:      event.dataTransfer.effectAllowed = 'move';
       //event.dataTransfer.setDragImage(ghost, 0, 0);
       //event.dataTransfer.setData("source_id", headerElem.dataset['id']);
  -    event.dataTransfer.setData("text/html", headerElem.dataset['id']);
  +    event.dataTransfer.setData(_DND_TYPE, headerElem.dataset['id']);
       // event.dataTransfer.setData('text/html', dragTarget.innerHtml);
     }
   
  
positive.code: import 'dart:html';
  
  Logger _log = new Logger('slick.dnd');
  
  class DragAndDrop {
    Element rootEl;
    Element _dragSourceEl;
  
negative.code: //    Element dropTarget = event.target;
      DivElement headerElem = findClosestAncestor(event.target, 'div.slick-header-column');
      //  DivElement srcHeaderElem = headerElem.parent.querySelector('#${_grid.uid}'+ event.dataTransfer.getData('source_id'));
      if (event.dataTransfer.getData(_DND_TYPE) != headerElem.dataset['id']) {
        if (!_grid.getEditorLock().commitCurrentEdit()) {
          //reject drop when have active editor
          return;
  