I've asked this elsewhere without getting a reply that works. I'm using a combination of cvt and xrandr as the basis of a script which adds the mode 1360x768_60.00 to the available options in Control Centre -> Monitor:
#Make screen resolution change
xrandr --newmode "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
xrandr --addmode VGA-0 1360x768_60.00
xrandr --output VGA-0 --mode 1360x768_60.00
I've set this up as a desktop icon and can run it inside a terminal. It works fine. A look in Control Centre -> Monitor confirms the change of resolution. Trying to set this as Default, however results in a a hiatus at the next boot and the OS reverts to 1920x1080. The monitor is a Benq 22.5in and the AGP card is a Radeon X800GT.
I wanted to make the change permanent so I guessed that I needed to enter the file to run somewhere in the boot sequence or to insert the nitty-gritty of the code into something that does run in the boot sequence. It was suggested that the place to insert the code was /etc/mdm/Init/Defaults. Unfortunately that does not work. I suspect that, even if that code does run, it is overwritten by some other file.
As an aside, the system looks nice but it is a PITA to make any adjustments. It seems to be a waste to have GUIs all over the show, which cannot be used and the superuser has to resort to command line manipulation.
I would be grateful for any advice or suggestions to get this done.