Carlos Garnacho shows how you can use CSS to style GTK+ apps. There are four other articles in English and Spanish in the new edition of GNOME Journal, including an interview with GNOME cofounder Federico Mena Quintero. He answers the question, “what is GNOME badly missing?”
Is always a placer to read Feferico Mena, is one of my favorites OSS developers.
Is if BOTH Gnome AND KDE used the exact same .css (or whatever) file for storing all the theme info.
KDE/Qt does support CSS themes. however, due to Qt’s C++ nature and the support of C++ namespaces, Qt’s CSS is probably not compatible with GTK’s.
Also afaik the CSS support in Qt is rather buggy and in general you should not use it. Also none is working on it anymore.
Right…Might as well ask for osx and windows to share theme files.
Why do you need that if you have QGtkStyle? http://code.google.com/p/qgtkstyle