[vtkusers] vtkFlRenderWindowInteractor problems resolved!

[Joshua A Foster]

All problems with vtkFlRenderWindowInteractor have been resolved.  It was just 
a bit of bad program design -- it turns out I did have two threads trying to 
update the window.  Fixed that, and all the other problems disappeared -- the 
X errors, the actors not showing up, and Render() not redrawing the window.  
Quite a relief...thanks, all responders, for your help.

Josh