Vector Addition Demo
With thanks to Volker Augustin and Julio Gea-Banacloche.
  1. You can draw two vectors on the work space.
  2. Vector 1 is shown in blue.
  3. Vector 2 is shown in red.
  4. The vector sum will be computed after pressing Add.
  5. The result is shown in magenta.
  6. The vectors in cyan complete the parallelogram.
  7. Pressing Clear will delete the preceeding action.
  8. Pressing Clear All will clear the work area.
  9. To exit press Quit.