Hi All,
I had also been having trouble switching backends, on winXP MPL 0.61. I found the reason for my problem:
import matplotlib
import myModule #myModule includes a "from matplotlib.matlab import mean" statement, which I hadn't thought of
matplotlib.use('GTKAgg')
from matplotlib.matlab import *
plot([1,2,3,4])
show()
#This doesnt work
···
###########################
import matplotlib
matplotlib.use('GTKAgg')
from matplotlib.matlab import *
import myModule
plot([1,2,3,4])
show()
#This does work