http://bugs.winehq.org/show_bug.cgi?id=59034
--- Comment #8 from Paul Gofman pgofman@codeweavers.com --- Thanks for checking this. I think I see what is the problem and it is still regressive with the blamed commit while is a completely different aspect / bug. With the initial issue fixed, the startup info show window flag is still not reset (as I mentioned before). Before the fix the flag was wrongly consumed on the initial window creation and thus wasn't affecting the exit dialog, while the fix still looks correct.
The exit dialog is just a MessageBox. After a lot of unit testing I figured that MessageBox behaviour is actually special WRT startupinfo flags. I updated the MR with more patches fixing these details: https://gitlab.winehq.org/wine/wine/-/merge_requests/9578
The updated MR should hopefully be fixing the exit dialog issue.