Matt, thanks for this info. I appreciate that you registered just to tell us about it. I have solved my problem with panning by patching and recompiling xorg, as described in that bug report mentioned above (I still use the solution for older version of xorg because I compiled it a while ago and then blocked updates to xorg).
But the solution with dummy VGA device seems interesting.
I guess the example you provided is for scaling. What command do you use for panning?
---------- Post added at 08:24 AM ---------- Previous post was at 12:45 AM ----------
OK, the question about panning was rather silly. It works.
Matt, I found that your solution works for me. Thanks, it is much easier than recompiling xorg.
My only question is how do you figure out the numbers in
xrandr --newmode "1280x720" 60.00 1280 1320 1376 1650 720 722 728 750
I understand 60.00, 1280, 720, but how about the rest? I realized though, that it seems to be OK to put zero in the remaining ones (although probably not optimal).
I guess that to make changes more permanent one could try to define the new mode in xorg.conf.