https://bugs.winehq.org/show_bug.cgi?id=54491
--- Comment #2 from Robert Naumann gonzomdx@gmail.com --- I found it out while synching wine Code to a forked regedit.exe in another project (which I will not mention here because it's not desired - I'm sure you know what I mean). On our side I worked around the bug with setting res to True before returning it, which seems more like a hack than a real fix. I'll give you our Bug ID CORE-18603 if you want to look at it. The return value is also checked in wine here: https://source.winehq.org/git/wine.git/blob/HEAD:/programs/regedit/framewnd.... but no error is observed because inside this code block is only a commented printf line.