OL, 03.12.2013 07:18:36:
I answer to myself this solution doesn't work, if the window is not at top and for a reason or another there is a redraw, you will not receive the WM_REDRAW. So the only solution is use USERDEF to redraw with VDI, I think if you want use such complex form object the best is to do yourself your dialog management in a window, I think.
I think that's what JFL wanted to avoid, and I can understand that. The AES should support such cases and not force the programmer to use home-cooked stuff or "dirty" things like USERDEF.
I would do a redraw on WM_SIZED/WM_MOVED or something but I'm not very familiar with the topic anyway.
-- Helmut Karlowski