Ubuntu Vibes shows you how to install Disper-indicator on Ubuntu

Disper-indicator provides a simple user interface for Disper display switching utility. Disper-indicator detects which monitors are currently connected to the computer and provides options to enable single screens, clone or extended screen configurations for systems having NVIDIA Cards.

Disper-indicator is based on Disper, an application written by Willem van Engen that lets you add and remove display devices.

  Disper Indicator, Easily Clone or Extend Displays on Multiple Monitor Setups