One more comment. I doubt this is the src of your woes, but don't do
from pylab import *
You can either use matplotlib in GUI / API mode (eg
examples/embedding_in_gtk*.py) or in pylab mode, which hides the GUI.
"show", for example, starts the mainloop, so you don't want to call
show and gtk.main.
FYI, it is a common complaint that the OO interface is not as well
documented as the pylab interface. The classdocs are pretty good
though, and there are plenty of examples in the examples dir. Robert
Leftwich also provides this tutorial
Assuming of course you can stop the thing from segfaulting