Wxpython backend finding the xpm bitmap files

I had matplotlib installed in another location, not under the

    > default python main tree and use the environmental variable
    > AFMPATH to point to the afm fonts files. The backend_wx(.py)
    > relies on distutils.sysconfig.PREFIX to find the GUI bitmap
    > files. Adding the following 2 lines

A number of people have reported problems with matplotlib in
non-default install locations. I'll try and get these cleared up
before the next release.

Thanks!
John Hunter