I'm using Xorg 7.5 on a Radeon HD4870 with the FOSS radeonhd server on my HP 6830s. The laptop has a VGA connector and I attach it to a 37" panasonic plasma TV. It works fine except for a little annoyance: when activated, the TV screen is set to the resolution of 1360x768 (which it reports as being the highest it supports) but all the image is shifted by about 100 pixels to the right. I can't see the leftmost part of the page, and I have a black vertical bar to the right.
If I change the resolution to 1024x768 there is no shifting, the image fills the entire screen with no parts hidden, but at this resolution the image is stretched.
How can I tune the position on the external monitor so that the image is centered in the screen filling it entirely?