The manpages are good for function reference, but they aren't usually
installed by default on most distributions.  I think Debian calls them
Xmanpages, but I don't remember for sure.  I haven't really seen any
X coding tutorials, but you could probably use the source of GDK
as an example.

Good luck,
Eden

From: "Julian M Catchen" <julian@catchen.org>
> Does anyone know a good book that teaches basic X programming?  Not
toolset
> programming (like GTK or QT) just basic X.  I am attempting to look at
some
> code that deals with X for the first time and could use a good
> tutorial/resource.
>
> I know that some of Oreilly's orginal books were on X, are these still
> relevant/in print?