How to tell Xubuntu not to clone but to expand the laptop display to the external one?

If you ran into the same situation like me:

1. Enter xrandr into your terminal and figure the name of your laptop screen and the name of your external screen. Mine were VGA-0 for the laptop and LVDS for the external one.

2. While you are on it you can figure the resolutions supported by both devices.

3. Create an executable script somewhere on your computer and name it e.g. dual_monitor.sh.

4. Put the following commands into the script. The comments should explain what is for what!

   #!/bin/bash
   
   
   # RESOLUTION SETTINGS
   # This sets your VGA1 monitor to its best resolution.
   xrandr --output VGA-0 --mode 1280x1024 --rate 60
   # This sets your laptop monitor to its best resolution.
   xrandr --output LVDS --mode 1400x1050--rate 60
   
   # MONITOR ORDER
   # Put the Laptop right, VGA1 monitor left
   # xrandr --output VGA1 --left-of LVDS1
   # Put the Laptop left, VGA1 monitor right
   xrandr --output LVDS --left-of VGA-0
   
   # PRIMARY MONITOR
   # This sets your laptop monitor as your primary monitor.
   xrandr --output LVDS --primary
   # This sets your VGA monitor as your primary monitor.
   # xrandr --output VGA1 --primary
   

   Just comment out what you don't want and uncomment what you need and you will be done - after running this script!

I got this solution from here and here.

Use the graphic interface of xrandr, called grandr. Install it as follows:

sudo apt-get update
sudo apt-get install grandr

Then go to systems -> Multiple Screens in the Xubuntu menu.

Here you can turn off the "Auto" checkboxes for the different displays and extend the layout in the layout screen. It works very well (Xubuntu 11.10 / Thinkpad x220).

For Xubuntu 13.04, the GUI frontend to xrandr is "ARandr"; works perfect!

apt-get install arandr