Thanks John and Andrew. Now I've changed my matplotlibrc
> to use the Agg backend by default. It would be nice if the
> default could be set appropriately on install, but I have
> no idea how one would do that. However, I doubt that GTKAgg
> is the default on Windows, so maybe there is a way!
I just change the default .matplotlibrc value when I build the windows
installer to tkagg. There's nothing automatic.
It would be nice if the setup.py script were smarter, and provided a
custom rc file depending on what it finds at build time (numeric vs
numarray, default backend) but there has been enough work to do just
getting core plotting functionality going (most recently contour and
polar) that configuration issues have been on the back burner.