[vtkusers] How to hide render window?

[Di Wang]

Hi peers-

This may be a trivial question-I need to change the transform matrix of 
some objects in order to let them move. I guess I must render them so 
that their position can be changed, but I don't want the render window 
to pop up, is there a way to shut down the render window and only run 
vtk in background?

Thanks a lot,
Dean