title: python interpreter doesn't display tkinter canvas
body: <p><strong>Here is my problem:</strong>
  Code from the book doesn't seem to work when I run it as a part of my script file. It nothing but executes: no errors, no canvas. After that it just waits for me to do something, like the command line is supposed to behave normally. If I print test line at the end of the script it prints as it should.
  <em>However</em>, code does work when I feed my python with it line by line. Copy-paste style.</p>
  
  <p><strong>Code:</strong></p>
  
  <pre><code>from tkinter import *
  tk = Tk()
  canvas = Canvas(tk, width=500, height=500)
  canvas.pack()
  </code></pre>
  
  <p><strong>My working environment:</strong>
  <em>Win 8.1, Win 10, PowerShell, cmd, Python 3.5.1</em></p>