John, I updated from CVS, made a one-line change to
> contour.py to add alpha support, and tested using
> contour_demo.py from bash shell--and found that with linux
> default gtk-agg backend, the gtk.main() doesn't return when
> the plot window is closed. I have to Ctl-C to get out.
Steve's recent change should fix your problem -- it was my bad.