XCB window needs a window manager
Fullscreen mode does not work if there is no window manager. Not that I really care but http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=537811
It is fixable but it would make the code more intricate - need to test whether EWMH is supported. Also, this is not going to work for if the desktop is larger than the view port (Xinerama, RandR and proprietary replacements) without further complications.