Hot screen resizing

openSUSE 11.2 x64, KDE_4.3.4
Geforce 9500GT, the latest Nvidia driver is installed
I have monitor and TV - both are the same resolution. Now i use twinView. It is ok until i want to play games - the picture is in the middle of screens. Now i must disable TV when i want to play.
I want to be able to resize my screens to one of them (3840x1080 → 1920x1080).
I think this can be done with xrandr, but i can’t understand how i can use it.

dima@host-120-5-75:~> xrandr -q
Screen 0: minimum 1920 x 1080, current 3840 x 1080, maximum 3840 x 1080
default connected 3840x1080+0+0 0mm x 0mm
3840x1080 50.0* 51.0
1920x1080 51.0

dima@host-120-5-75:~> xrandr -s 0
dima@host-120-5-75:~> xrandr -s 1
Failed to change the screen configuration!

Any help is appreciated

The NVIDIA driver doesn’t support xrandr 1.2, only earlier versions. Not sure if changing screen resolution (and output target) on the fly is a 1.2 feature but I suspect that’s your problem.

Then what can i try else except xrandr to resize screen on fly?
What is the best practice in linux for that? I hope i am not the only one who has dual monitor configuration.

Not sure, someone else might come up with something. Assuming my explanation is the correct one, it’s not really Linux’ fault but NVIDIA’s. I suspect xrandr will do what you want if you don’t use the proprietary NVIDIA driver. I had a similar problem with rotating just one of two monitors on an NVDIA dual-head, just can’t be done because of the poor xrandr support and the built-in limitations of Twinview.
You’ll probably have to make do with a restart of X… Unless someone here knows differently.