The Settings Manager -> Display on my DECTOP running Xfce is set to Default and only has 800x600 and 640x480 as options -- the machine can display up to 1600x1200 and my Dell Screen likes 1280x1024 -- I changed my /etc/X11/xorg.conf to include 1280x1024:
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
Then I rebooted expecting it to come up in 1280x1024 -- but it still looks like 800x600 -- anyone suggest any other approach... thanks.
I am having a similar problem with xfce 4.4x I installed to opensuse 11 (kde): If I boot into runlevel 3, login and type "startxfce4" in the cli, it starts xfce desktop in full, 1280x1024 resolution.
But if I choose xfce from the kde 4 login Session menu (which is the preferred way), I get maximum resolution of 800x600 ("default") and 640x480 as the only other setting, even though I changed xorg.conf as described in the original post.
I had a similar problem where no matter what I had on the xorg.conf file, it came up as 800x600. I finally solved it by running xorgcfg -textmode, and selecting my settings from there--i was able to run 1280x1024 and 1024x768 in addition to 800x600. I have no idea WHY it solved the problem, fortunately, but it did.