[vtkusers] CPU usage while dragging the window ? (Mac OS X)

[Marius S Giurgi]

(I was wondering if this is a Mac OS X, Tcl or a VTK issue)

I was playing with the "VolumeRenderWithBoxWidget.tcl" example (in 
/VTK/Examples/GUI/Tcl/) which renders quite slowly being a volume 
rendering, and I noticed that dragging the whole window around it's 
very slow and uses a lot of CPU; it's almost like the rendering 
pipeline is being activated continuously (updated) as the window moves 
(and it shouldn't as nothing gets changed while dragging the window). 
Is there a way to prevent this from happening? Is this behavior normal?

thanks,
marius