[vtkusers] Change Render Window

[Kall, Bruce A.]

How do you correctly change (and update?) the render window's window id?
I'm running under Xwindow and can successfully create my own X window and
set the vtk renderer to render into it.  I have 4 of the same sized 
windows on my screen
and want to periodically change which of the 4 X windows
vtk renders into (all are the same size, depth etc).

If I set everything up and set the initial X window by 
renWin->SetWindowID(window)
and then render into it, it works just fine.

If I then call renWin->SetWindowId(new_X_window_id) and then render I get
a "GLXBadDrawable" as an Xwindows error.  I've tried 
renWin->MakeCurrent() and
renWin->Start()  after the renWin->SetWindowId() and before the 
renWin->Render()
and neither fix the error.

It seems like there should be some type of renWin->Update(), but there 
isn't.

What step am I missing?

Thanks,
Bruce