https://bugs.winehq.org/show_bug.cgi?id=56045
--- Comment #3 from claytmp+foj0w@gmail.com --- (In reply to Fabian Maurer from comment #1)
Seems to work for me in clean WINEPREFIX. Is there anything else need to reproduce?
Sorry, I uploaded wrong exe file that doesn't have RichTextBox, try "Updated exe file" from attachment. The RichTextBox background is black with text foreground as white. I also replicated the issue in clean WINEPREFIX