 Dropdown = (opts = {}) ->
   defaults =
     showing: false
+    persistent: false
     direction: Direction.SOUTH
     align: 'center'
     x: 0

    list.set(key, null)

  removeAll = ->
    Object.keys(list.keys).forEach(remove)

  create: add
  get: get

DropdownsStruct = ->
  list = new ReactiveDict()

  allKeys = ->
    Object.keys(list.keys)

  except = (keys) ->
    _.without(allKeys(), keys...)

  get = (key) ->
    list.get(key)
