Hello,

> > Can the user devote some time to testing patches?
> 
> As I can't compile something without seeing my X server crash a
> few minutes later and as I need my laptop to work in the evening,
> I can test fully compiled X servers but, unfortunately, not test
> source patches.

Grab this one
http://macallan.homeunix.org:6704/stuff/BSD/XFree86_server_macppc.tar.bz2 - it's a slightly patched XF4.4 ( Server and modules only, no libraries, you'll need a halfway recent -current install to run it ) compiled for NetBSD 2.99.10 / G3 ( but has been reported to work on 604 and G4 machines ). It should either be stable or not work at all :)
If it's stable then you have the problem described (and cured) by Aymeric.

good luck
Michael