title: I am unable to get urwid tutorial examples to work
body: <p>Being new to both Python and urwid I was trying out the tutorial examples here <a href="http://excess.org/urwid/docs/tutorial/" rel="nofollow">http://excess.org/urwid/docs/tutorial/</a></p>
  
  <p>However while the first ones do work fine, most of the later ones do not seem to work. For instance, trying to run this particular one:</p>
  
  <pre><code>import urwid
  
  choices = u'Chapman Cleese Gilliam Idle Jones Palin'.split()
  
  def menu(title, choices):
      body = [urwid.Text(title), urwid.Divider()]
      for c in choices:
          button = urwid.Button(c)
          urwid.connect_signal(button, 'click', item_chosen, c)
          body.append(urwid.AttrMap(button, None, focus_map='reversed'))
      return urwid.ListBox(urwid.SimpleFocusListWalker(body))
  
  def item_chosen(button, choice):
      response = urwid.Text([u'You chose ', choice, u'\n'])
      done = urwid.Button(u'Ok')
      urwid.connect_signal(done, 'click', exit_program)
      main.original_widget = urwid.Filler(urwid.Pile([response,
          urwid.AttrMap(done, None, focus_map='reversed')]))
  
  def exit_program(button):
      raise urwid.ExitMainLoop()
  
  main = urwid.Padding(menu(u'Pythons', choices), left=2, right=2)
  top = urwid.Overlay(main, urwid.SolidFill(u'\N{MEDIUM SHADE}'),
      align='center', width=('relative', 60),
      valign='middle', height=('relative', 60),
      min_width=20, min_height=9)
  urwid.MainLoop(top, palette=[('reversed', 'standout', '')]).run()
  </code></pre>
  
  <p>Presents me with the following error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "example.py", line 23, in &lt;module&gt;
      main = urwid.Padding(menu(u'Pythons', choices), left=2, right=2)
    File "example.py", line 11, in menu
      return urwid.ListBox(urwid.SimpleFocusListWalker(body))
  AttributeError: 'module' object has no attribute 'SimpleFocusListWalker'
  </code></pre>
  
  <p>Am I doing something wrong?
  If it helps in any way I'm running Ubuntu 12.10 64bit.</p>