Xorg - how to disable some video modes?

[User Gandalf]

>
> gah, xfce4's control panel doesnt do that for me, though it used to on 
> another older notebook i was using. for the life of me i cant remember 
> what i did to make this happen then and not not. my xorg.conf is minimal.

Which version are you using? I may be a new feature?

4.2.3.2 (Xfce 4.2)

>
> using xvidtune or ctrl-atl-numpad+ does switch video modes, but the 
> virtual screen remains at the larger 1400x1050 size, thus giving that 
> pan effect. would anyone hit me with a cluebat[1] on how to fix this ?

I have an Intel i810 card, and xvidtune does not support it. :-( I 
cannot help you with this.

   Les