[vtkusers] Conditional text positioning/scaling?

[Alex Malyushytskyy]

I am looking for the way to have non-scaled text unless text can't fit
specified in normalized viewport rectangle.
Something very similar to the vtkCornerAnnotation,  but
sizing/scaling has to be done within rectangle defined  in normalized
viewport coordinates instead of whole viewport.
I could not find how to achieve this with vtkTextActor.or any other class.

Is there a class which can provide what I am looking for? It sounds
the most reasonable way to display 2D annotations, so it would be a
bit strange if it was not available yet.

Thanks in advance,
   Alex