   onDragOver: (e) =>
     return unless @treeView.list.contains(e.target)
 
-    unless e.dataTransfer.getData('atom-tree-view-event') is 'true'
+    unless @isAtomTreeViewEvent(e)
       return
 
     e.preventDefault()

    {dataTransfer} = e

    # TODO: support dragging folders from the filesystem -- electron needs to add support first
    return unless dataTransfer.getData('atom-tree-view-event') is 'true'

    fromWindowId = parseInt(dataTransfer.getData('from-window-id'))
    fromRootPath  = dataTransfer.getData('from-root-path')

    e.target.closest('.project-root-header')

  isDragging: (e) ->
    for item in e.dataTransfer.items
      if item.type is 'from-root-path'
        return true

    return false

  isAtomTreeViewEvent: (e) ->
    for item in e.dataTransfer.items
      if item.type is 'atom-tree-view-event'
        return true

    return false

  getPlaceholder: ->
    unless @placeholderEl
