[vtkusers] visibility of texture-based actors in volume renderings

[Dean Inglis]

Can someone explain this to me so that I
can possibly rectify vtkImagePlaneWidget (IPW)?

If I add the widget to a pipeline by setting
 the interactor for the IPW, and setting the widget to 
its enabled/on state before adding
a volume to the rendering pipeline, I see both
the widget's slice and say a transparent 
texture mapped volume.  If I turn off and
then turn back on the widget or if I add the
volume to the renderer before setting the 
widget's interactor the sliced image is non-existent
but the widget's outline is visible.

Dean