#12 Simplify DnD code

[Peter Becker]

The drag and drop code as found on the diagram
organizer components is probably far too complicated
for a program that requires JDK 1.4 anyway. The new JDK
1.4 features should make the DnD support a lot easier,
as described here:

http://access1.sun.com/tutorials/Swing_Tutorial/Dnd-Merlin-Tutorial/1.html