https://bugs.winehq.org/show_bug.cgi?id=53826
--- Comment #16 from PeterG peter.g.anderson@live.co.uk --- Having looked at the Battle.net installation process I have noticed that as Battle.net is installing, various folders and files are created in the wineprefix.
When the problematical qwindows.dll file is created it is initially called something like .qwindows.xxxx.dll.tmp and is subsequently renamed (moved) to qwindows.dll Because this temporary filename starts with . it is seen by Linux as a hidden file and wine applies the h DOS attribute. However, this attribute remains after the file is renamed to qwindows.dll which causes the problem when Battle.net Launcher.exe tries to run, as it can't find the hidden file.
Perhaps we need a piece of code in wine to check whether the 'hidden' DOS attribute applied to a .file needs to be removed if a file is renamed or moved.