code: function(event) {
  				var sourceNode = $.ui.fancytree.getNode(event.target);
  				if(!sourceNode){ // Dynatree issue 211
  					// might happen, if dragging a table *header*
  					return "<div>ERROR?: helper requested but sourceNode not found</div>";
  				}
  				return sourceNode.tree.ext.dnd._onDragEvent("helper", sourceNode, null, event, null, null);
  			}
docs: Let source tree create the helper element