Sorry for the late response. I can confirm that the patch is working.
I am one step further in solving this conundrum. The reason why some icons show up, but most don't is because qt5ct drops the theme name mid-air. At the beginning of the application lifetime, it is still "application", so a few of our icons are loaded, but then suddenly the theme name becomes "", which forces Qt to fall back to the system icon theme resulting in some system icons being shown, but most icons being empty. This looks extremely buggy to me. I can work around the issue by adding a redundant...
Might be related to issue #66. https://sourceforge.net/p/qt5ct/tickets/66/
Might be related to isue #66.
qt5ct breaks QIcon::fromTheme()
It's not obvious to the users. It's not even obvious to me until I check what the generation feature actually generates, because it's documented nowhere.
Oh, and BTW, interesting anecdote: I lost count of the times that users coming from KeePass had questions about or problems with keyfiles and thought we were doing something funny while KeePass would supposedly just use "any" binary file as a key file. None of them noticed they actually had an XML file and we were in fact the ones using "any" file by default until we explained it to them. Somehow there is this misconception that KeePass uses arbitrary binary files as key files, while in reality it's...
Encoding doesn't matter, unless you transfer it via FTP in text mode or have some other bad ideas about how to willfully ruin your data. Opening and editing a key file isn't any more a use case than opening and editing the KDBX file, which is a binary file as well. I see no advantage in XML files whatsoever.