https://bugs.winehq.org/show_bug.cgi?id=14901
--- Comment #36 from redneb@gmx.com --- I wouldn't say it is. While the behavior has now improved, as it does not return an error anymore, you still cannot change the case of the letters of a filename, i.e. you cannot rename "test.txt" to "TEST.TXT". If you try to do that, no error will be reported, but the filename will remain "test.txt".