Under unity7/xorg it's possible to configure the position of the screens and their geometry, that includes
- resolution of each screen
- rotation possible
- relative position (external on top of laptop, or on the right)
- definition of a "primary" monitor (the one containing the launcher if you decide to have that UI element only on one screen)
- etc
Under unity7 the configuration is applied on login by unity-settings-daemon using xrandr. In the new world unity8 should probably be the one setting up the configuration at start
Under unity7/xorg it's possible to configure the position of the screens and their geometry, that includes
- resolution of each screen
- rotation possible
- relative position (external on top of laptop, or on the right)
- definition of a "primary" monitor (the one containing the launcher if you decide to have that UI element only on one screen)
- etc
Under unity7 the configuration is applied on login by unity-settings- daemon using xrandr. In the new world unity8 should probably be the one setting up the configuration at start