The method dragExit is called before drop. This is bad because it prevents
the method from being used to clean up if a drop was not performed. For
example, in Swing a selection point is moved around over the target to
indicate where a drop would occur if performed. If a drop is not done the
DropTargetListener should restore the original selection state to the component.
When dragExit is called, it is not yet known if a drop has happened. The
dragExit method should be called after drop, not before.