[vtkusers] drawing with OpenGL primitives within Paint() in a sub-class of vtkContextItem

[Paul Douglas Hahn]

Does anyone know if it is feasible to call OpenGL2 primitives directly 
within the overridden Paint() method of a sub-class of vtkContextItem 
(i.e., as found in Rendering/Context2D)? I am using VTK 8.1 specifically.

If so, is there an example somewhere?

Thanks!

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