# Generic (leaf)

A placeholder, intended to be taken over by the application. Should always be given a name, so the application can access it. Often has some application-defined interactive behavior. Until taken over, this has the shape and appearance of
`(Shape (Width 0 + 0) (Height 0 + 0) "")`

Notes
  To take over a Generic, use `PutGeneric`; to retrieve the VBT, use `GetGeneric`. A Generic is implemented as a Filter.T, whose child is the VBT specified using `PutGeneric`. Whenever `PutGeneric` is invoked, the size of the new VBT is propagated appropriately. Generic should be used only when there is no comparable interactor provided by FormsVBT, or when the VBT will change dynamically. If you want to use a subtype of an interactor, you should override the `realize` method of the FormsVBT object; see `FormsVBT.i3`.