title: timer that calls every n milliseconds a function without .after or threading
body: <p>I need a timer that calls a function every n milliseconds.
  This should not be in a endloss loop (while true) or something like that</p>
  
  <pre><code>import threading
  
  def printit():
     threading.Timer(5.0, printit).start()
     print "Hello, World!"
  </code></pre>
  
  <p>Or </p>
  
  <pre><code>def printit():
      root.after(100,printit())
  </code></pre>
  
  <p>As I have a GUI that should be able to interact. So that I can stop the timer.</p>
  
  <p>Some ideas?
  Thanks!</p>