https://bugs.winehq.org/show_bug.cgi?id=48955
--- Comment #2 from Olivier F. R. Dierick o.dierick@piezo-forte.be --- Hello,
My opinion is that it would be impractical to split the wineprefixes in 3 parts and it's not worth the effort.
Support for XDG standard is application-specific design. Wine runs Windows applications. They are not XDG compliant and Wine can't do anything about it.
We could split 'well known' paths that theoretically contain config (registry files), cache (temp dirs) or data (ProgamData, Program Files, Windows) files, but the Windows application itself will never cooperate. It can put files anywhere. It's best to consider the wineprefix as a single, independent, hierarchy that follows the 'Windows' standard.
Keep in mind that ~/.wine is only the default wineprefix and most users have more than one wineprefix. How would Wine deal with multiple wineprefixes with those XDG_*_HOME settings?
What would become of the WINEPREFIX variable and things that depends on it/expect the files to be in a single location?
The use of single-directory wineprefixes is a long-standing thing and changing it will cause lot of trouble (Broken scripts and angry users) for no benefit at all. It'll require a global redesign of Wine's wineprefix management.
Not everyone wants to mix Wine stuff with their normal user files. Not everyone wants to use their XDG configuration for Wine stuff.
I'm sure they are other arguments against the use of XDG standard for wineprefixes.
If all you want is to unclutter your home directory by moving ~/.wine away, just put it wherever you want (in your XDG_DATA_HOME if you wish so) and set WINEPREFIX to the new location when invoking Wine.
Regards.