In case this helps someone else...
When I switched from 12.1 to 13.0 for everyday use, the only real pain was that my dualhead monitor setup no longer worked. I really need this for work and back when I installed slack 12.1 I got a good solution with xrandr for spanning across internal+external 19" monitors as described clearly
here.
intel pre-i965 (mine is 945gme) won't do dri if the Virtual in xorg.conf is set greater than 2048, but my width is 1440+900>2048. In slack 12.1 I just turned dri off with an option in xorg.conf and the problem was solved - don't play games at work
But, in slack 13.0 the new xorg seems to ignore all requests to turn off dri and so I couldn't get past the >2048 issue with xrandr. When I finally did manage to clobber dri (Disable "glx" did it I think), I had terrible graphics performance and still got the >2048 error from xrandr! Seems a partial explanation can be found
here.
Trying to use Xinerama in the xorg.conf (which was my solution back in slack 11 days) resulted in a complete crash on starting X - not an EE in the log, a full on crash.
Early on I'd come across this
page and the second solution it described didn't make sense to me, so I had ignored it. But, since nothing else worked, I copied and pasted it into my xorg.conf and bingo! I now have dualhead with a width of 1440+900 and I also have dri, which I thought wasn't possible on this intel chipset with width>2048!