We all know since 2006 (?) that the world is turning to use XCB instead Xlib as the interface between X clients and the server. The advantages of using XCB is well know but, even so, it’s being adopted very slowly for some reason – for instance no toolkits yet ported it. If this serves as a motivation, Alan got a really nice measurements porting a simple X app.
Translate your toolkit and application now! :)