title: Canvas does not appear python 2
body: <p>I am running a simple little test program in python 2, but the canvas is not appearing.</p>
  
  <pre><code>    from Tkinter import *   
      tk = Tk()   
      canvas = Canvas(tk, width=600, height=600)   
      canvas.pack()   
      canvas.create_rectangle(250, 250, 350, 350)
  </code></pre>