     event.preventDefault()
     newDropTargetIndex = @getDropTargetIndex(event)
     return unless newDropTargetIndex?
+    return if @lastDropTargetIndex is newDropTargetIndex
+    @lastDropTargetIndex = newDropTargetIndex
 
     @removeDropTargetClasses()
 

      false

  onDragLeave: (event) ->
    @removePlaceholder()

  onDragEnd: (event) ->
    return unless matches(event.target, '.sortable')


  onDragStart: (event) ->
    return unless matches(event.target, '.sortable')
    @lastDropTargetIndex = null

    event.dataTransfer.setData 'atom-event', 'true'

