Switch two screens with xorg.conf tweak

I have a monitor on the left and TV - as a monitor - on the right and I was happy with unintended dual monitor by installing nvidia-glx package. Four workspaces of Xfce at first 'were' like 1920x1200 (monitor) + 1920x1080 (TV) so eventually 3840x1200 for each. A couple of days ago I don't know why but I thought maybe I don't need the TV screen, so I ran Xfce menu -> Settings -> Screen and tested the screen setting by disabling and enabling each screen, ... it was a beginning of a disaster.

Workspaces were not 3840x1200 anymore, it became 1920x1200 on TV. It looked like Xfce doesn't involve my monitor screen in its workspaces and I couldn't move application windows from a monitor to TV or vice versa. In advance, panels and desktop icons of Xfce moved TV, (they were on the monitor screen) two screen were switched! I couldn't roll back with Xfce menu -> Settings -> Screen so embarrassed.

Now I think I could tweak some of xml files like displays.xml or xfce4-desktop.xml in ~/.config/xfce4/xfconf/xfce-perchannel-xml/ directory (I'm using Xfce 4.8) but I didn't know at that time and my trials with xrandr command created by arandr in ~/.bashrc didn't make me satisfied because the screens were blinked once again after log in Xfce session. They say put the xrandr command in a gdm script of /etc/gdm/ but couldn't make it.

I googled more & solved the problem with /etc/X11/xorg.conf tweak. (There was no xorg.conf in /etc/X11 by default any more and I welcomed it but I had to create xorg.conf to solve this problem.)

I tried with NVIDIA X server settings in Xfce menu -> Settings but it didn't work because the xorg.conf created by that NVIDIA program was using two more "Device" sections for my one GeForce GT 630 card and Xfce seniors say Xfce doesn't support that. So I deleted the nvidia Device sections and modified the first section of xorg.conf, "ServerLayout" section like below by an advice of the following link.


Section "ServerLayout"
        Identifier     "X.org Configured"
        Screen      0  "Screen0" RightOf "Screen1"
        Screen      1  "Screen1" 0 0
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"
EndSection

http://forum.xfce.org/viewtopic.php?id=6495

It worked perfectly! The screens are switched with Xfce panels and icons as it was before and expanded workspaces through two monitor screens came back.