I found the DragnGhostDemo code example and tried it.
Your question raises many possibilities.
The DragnGhostDemo drags images of JLabels, JButtons and a JTable.
Java drag_n_drop is
not designed to drag buttons and labels and will drag data from tables. So implementing
drag_n_drop on some of these components using TransferHandlers doesn't seem feasible.
It is easy enough to drag and drop these components without using TransferHandlers. The
way the DragnGhostDemo app is put together it appears that it would be easy to modify it
to do this. You would have to work out the drop target part, ie, how to deal with the
dropped component.