title: cv2.waitKey(0) not working, OpenCV 3.1.0, Mac OS X 10.11.6, Python 2.7.12
body: <p>I have these two statement in the end of my python program:</p>
  
  <pre><code>cv2.waitKey(0)
  cv2.destroyAllWindows()
  </code></pre>
  
  <p>Somehow cv2.waitKey(0) not working, no response to keyboard input 0, to end my program I had to close my Mac terminal window.</p>
  
  <p>I tried the following to fix the problem</p>
  
  <pre><code>if cv2.waitKey(0) &amp; 0xFF == ord('q'):
      break
  </code></pre>
  
  <p>then I got this message:
  SyntaxError: 'break' outside loop</p>
  
  <p>Not sure what's wrong. I am using a Macbook Air, Mac OS X 10.11.6
  Please help.</p>
  
  <p>Thanks</p>