I found out that: 1. Using LeLisp's packaging system i only have to define one mouse-function: {ctedit}:popup:undo:mouse-up 2. The area covered by the popup menu is correctly redrawn. So this is some clipping problem. 3. Even the following function call does not help: (send 'redisplay ctedit (rectangle 0 0 (send 'height ctedit) (send 'width ctedit))) - Thomas -