I've tried this demo from your website:
http://matplotlib.org/api/widgets_api.html?highlight=matplotlib.widgets#matplotlib.widgets.RectangleSelector

But at the moment of runnig your program I've this error:

File "rec.py", line 1, in
from matplotlib.widgets import RectangleSelector
File "/usr/lib/python3.2/site-packages/matplotlib/init.py", line 105, in
import os, re, shutil, subprocess, sys, warnings
File "/usr/lib/python3.2/subprocess.py", line 378, in
import select
File "/home/simone/spz/select.py", line 1, in
from pylab import *
File "/usr/lib/python3.2/site-packages/pylab.py", line 1, in
from matplotlib.pylab import *
File "/usr/lib/python3.2/site-packages/matplotlib/pylab.py", line 222, in
from matplotlib import mpl # pulls in most modules
File "/usr/lib/python3.2/site-packages/matplotlib/mpl.py", line 1, in
from matplotlib import artist
File "/usr/lib/python3.2/site-packages/matplotlib/artist.py", line 6, in
from matplotlib import docstring, rcParams
ImportError: cannot import name rcParams

I'm using the GIT version with python 3 under ArchLinux.
But I've observed the same problem with matplotlb 1.1.1 on python 2