https://bugs.winehq.org/show_bug.cgi?id=44404
--- Comment #3 from Louis Lenders xerox.xerox2000x@gmail.com --- (In reply to Fabian Maurer from comment #2)
Are you using overrides? Because I get
System.EntryPointNotFoundException: Unable to find an entry point named 'SetWindowThemeAttribute' in DLL 'UxTheme.dll'.
I sent a patch for that to wine-devel but it did not (yet?) appear. The patch is in other bugreport for B4A in bugzilla