We gonna take care of updating this link. Sorry for the inconvenience.
You're accessing the conversion of the Xlib Programming Manual into HTML, brought to you by Christophe Tronche. This work is far from being complete, as you're noticing now, and is provided "as is" ("as usual"). Many links have been made provision for, but actually aren't translated yet. If you're more interested in some part of the manual, let me know and I'll push further on it.

This work is based on X11 release 6.

The X11/Xlib manual is copyrighted by the X Consortium.