swing.FileChooser should be a Component

[Sciss]

From scala/bug#1824

the swing lib shows

class FileChooser(dir : java.io.File) extends AnyRef

but JFileChooser sends PropertyChangeEvents and ActionEvents.
This feature is essential e.g. for accessory components.

http://java.sun.com/docs/books/tutorial/uiswing/components/filechooser.html#accessory