https://bugs.winehq.org/show_bug.cgi?id=57070
--- Comment #6 from Hanabishi i.r.e.c.c.a.k.u.n+bugs.winehq.org@gmail.com --- No, applying this MR doesn't seem to change anything.
Although, upstream dev responded with explanation:
cnc-ddraw does also have some special logic to handle the RA2 child windows, it does actually use GDI BitBlt for them and not OpenGL (There's still a opengl context being created and used for the main window though). Direct3D9 and GDI renderer also use the same BitBlt trick on the menus.
Also confirmed by setting a workaround option:
Just for a test, could you try to set "fixchilds=3" in ddraw.ini? That would hide the child windows and also disables the bitblt. This is not actually a good thing to do, but maybe it would help to find out what's wrong.
Disabling BitBlt mitigates the issue.