[vtkusers] Problem adding actor to a renderer

[Roger Blum]

Hello

My Tcl application has 2 renderers: 1 showing an overview window and 1 
showing the interactive window where user can zoom, pan, etc.

The background in both windows is a bitmap displayed with a 
vtkImageActor. This used to work perfectly till recently the overview 
window stopped showing the image. I can not find the reason for this 
sudden change.

I' ve found that the actor doesn't get added to the renderer. Writing 
output before and after the AddActor command shows that the renderer has 
the same amount of actors before and after the call.
If I try to add the actor 'manually' from the built-in shell I can add 
it to the main window but it wouldn't add to the overview window.

What would cause a renderer to not accept an (obviously correctly 
configured) actor?

Thanks for any help in solving this mystery,
Roger