Mode for files visited by GUD

[Juanma]

Hello all,

Is there any mode (and it's hook) run when GUD visits a source code file
during debugging?

I have found a gud-minor-mode variable, but it's not documented. Anyway,
quickly peeping into the source, it doesn't seem like that minor mode would
serve my purpose.

Actually, many functions and variables are not documented. I'm not helping,
so I'm not complaining. I'm just curious, because I find it odd for a mature
package (GUD has gone along with Emacs since a very long time ago, right?)
to have many things left undocumented.

BTW, is Emacs' CVS repository, under emacs/lisp/progmodes, the right place to
find the latest version?

Thanks.
-- 
Juanma

"Having a smoking section in a restaurant is like
 having a peeing section in a swimming pool."
       -- Edward Burr