http://bugs.winehq.org/show_bug.cgi?id=2082
--- Comment #128 from Vincent Povirk madewokherd@gmail.com ---
The ultimate result is that dialog D obscures window A. I haven't investigated why dialog D is all black as opposed to looking like a typical user32 dialog window with controls.
This is because (on Windows, at least before compositing was introduced and before Windows 8), although ddraw will ignore clipping and draw over other windows, it does not prevent those other windows from also drawing. To prevent ddraw from fighting user32 and causing flicker, WA intentionally prevents the dialog from drawing (on older versions that prevention was flawed and you'd sometimes get flicker anyway, but they may have fixed that). It happens that WA does not need to do any gdi drawing at all, but other programs use clipping to mix ddraw with gdi, and there may be a few that do not use clipping but instead manually synchronize ddraw and gdi drawing (diablo maybe?).