[vtkusers] Disable lighting per-actor

[James Turner]

I was wondering if there was a method to disable light at a per- 
actor / prop granularity in a renderer? I'm displaying some 'helper'  
actors alongside my main data, principally some wireframe boxes, but  
the box edges are being lit, which looks odd; I'd like each box to  
appear as a flat color that I assign, presumably via  
vtkProperty::SetColor, although the docs indicate that simply sets  
the diffuse and specular terms, which may not be quite what I want.

In raw OpenGL, I'd just glDisable(GL_LIGHTING) whilst rendering the  
primitives in question, but of course that's not an approach that  
makes sense in VTK. What are the alternatives?

Thanks,
James