Funnily enough I've been writing a pure-Smalltalk X11 protocol implementation recently, for Squeak, and it starts to have some of the feel you describe. It generates Smalltalk code from the XML xcbproto definitions. It's at the point now where you can send X11 requests interactively in a Workspace, etc., which is fun ("playing with a dynamic Smalltalk interpreter"), and I'm working on integrating it with Morphic. Anyway, thought you might enjoy the idea.