Discovered on windows - here are the steps we followed to cause it .

Run the JumpingBox demo applet.
Make the applet window large.
From the applet menu, open the print dialog, and drag it on top of the
applet window. It is not necessary to drag vigorously.

The box will draw pieces of itself in random positions and leave the
pieces lying on the screen. Dragging the dialog leaves pieces of box
behind it (not pieces of Dialog).

Observed with 1.2fcs, 1.2.2 and Kestrel-K.