title: I can't get tkSimpleDialog to work in python
body: <p>I have the following python test program. When I run it I expect to be able to click on the "Dialog" menu and select "Show Dialog" and have the dialog box pop up. Instead I get:</p>
  
  <pre><code>Exception in Tkinter callback
  Traceback (most recent call last):
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1532, in __call__
      return self.func(*args)
    File "testdialogs.py", line 13, in dialog_show
      result = tkSimpleDialog.askstring('Result', 'Where to next?')
  AttributeError: 'module' object has no attribute 'askstring'
  </code></pre>
  
  <p>As you can tell this is on a Mac running python 2.7.</p>
  
  <pre><code>import Tkinter as tk
  import tkSimpleDialog
  
  root = tk.Tk()
  
  canvas = tk.Canvas(root, 
              width=1000, 
              height=500)
  
  canvas.pack()
  
  def dialog_show():
      result = tkSimpleDialog.askstring('Result', 'Where to next?')
  
  menu = tk.Menu(root)
  
  dialog_menu = tk.Menu(menu)
  
  dialog_menu.add_command(label="Show Dialog", command=dialog_show)
  menu.add_cascade(label="Dialog",menu=dialog_menu)
  
  root.config(menu=menu)
  root.mainloop()
  </code></pre>