https://bugs.winehq.org/show_bug.cgi?id=42284
--- Comment #6 from Vincent Povirk madewokherd@gmail.com ---
Would it be possible map calls into GTK, QT, or equivalent toolkit that know how to draw directly on a wayland buffer?
This would not solve the problem Michael described. These toolkits are able to correctly position drop-down menus because they know which main window the menu belongs to, and can request positioning relative to that. Wine does not generally have this information and would have to guess.
I don't think the problem is insurmountable, but then again I didn't do the work.