I'm dipping my toe into the world of theming for Gnome and Xfce. I really can't seem to find any decent documentation on theming using GTK or GTK2 at ALL. I've looked through here for similar threads, googled till I thought my head would explode and attempted to work on a theme myself. I can't really seem to get anything decent - with the exception of MAYBE my 'Tangoish' Theme(available at art.gnome.org and gnome-look.org) but even that uses the default rendering engine and truthfully I'm not sure how to change it. Any help would be greatly appreciated.

There is a tutorial on art.gnome.org