Hello,
I just want to thank you for Wine and show you my own uxtheme.dll implementation, which uses the GTK+ rendering engine. Thus Wine applications look really native for users.
Here is the link: https://github.com/akulinchev/uxthemegtk (see the screenshots at the bottom of the page)
If you want, I can help you to add it to the Wine code. If not, I will develop it alone as a third-party project, but then I have a question: what is the best way to replace a Wine library? I think, I shouldn't change anything in /usr/lib/wine. I know about "native libs", but it's an ELF binary, not PE.
Regards,
Ivan