[vtkusers] Add a Rectangle Actor to VTK RenderWindow

[Alex Southern]

Hi chaps,

I'm looking to add a rectangle (made up of just 4 lines with no fill 
color) to the render window.

I want to be able to set its size and position and alter these with QT 
sliders. Ive got the QT side of this covered all set and ready to go, 
but what is the best way to create the rectangle in VTK?

Thanks
Alex
-- 

Alex Southern
Researcher
Aalto University
School of Science,
Department of Media Technology,
PO Box 15400, FI-00076 Aalto, Finland