https://bugs.winehq.org/show_bug.cgi?id=34375
--- Comment #6 from winetest@luukku.com --- (In reply to Kevin Meyer from comment #5)
This isn't fixed, going fullscreen sets Always On Top to true, and then going back to windowed leaves that flag set to true.
Do you remember the wine version? It's impossible others to know what wine you have tested. I don't expect this to be fixed meanwhile, but if is not too much an effort it would be good if you could retest with more recent wine.