To reproduce(JDK1.1.5 + Swing-Pre-1.0(2/3) + WindowNT):
1) click "internal frame" tab from the SwingSet demo.
2) check is Maxable and Iconifiable box.
3) create one internal frame.
4) first maximize it( when you can't see the title bar, resize SwingSet)
5) then minimize it.
6) click maximize button.
7) It will restore original size instead of maximizing it.

It is true in all look and feels.