title: Progressbar (ttk.Progressbar) with python in tkinter not showing
body: <p>Using the <strong>ttk.Progressbar</strong> in Python (in a tkinter GUI), I'm trying to have a progressbar appear when I press a button. Clicking the "Analyse" button on the gui calls the function analyze in the script, which I've meant to be a three-stage rocket of sorts:</p>
  
  <ol>
  <li><p><strong>grid()</strong> the progressbar-widget to add it to the mainframe, and <strong>start()</strong> it. </p></li>
  <li><p>Do the actual computing (which takes about three seconds in my
  test-runs)  </p></li>
  <li><p><strong>stop()</strong> the progressbar and <strong>grid_remove()</strong> it to hide it from the user again, now that the job is complete.</p></li>
  </ol>
  
  <p>If I comment out step <strong>3</strong>, the progressbar will be shown and started as expected, while step <strong>2</strong> is executed. But if step three remains, the progressbar is never shown in the first place. Now, since the work in step two is being executed either way, I'm assuming that it might have something to do with gridding and removing of the progressbar-widget in the same function-call, but since this is my first real gui project in python, I'm a bit at a loss on how to work around that (if that indeed is the problem). Is there a way around this, or a way of more elegantly accomplishing the same task? The function the button calls is as follows:</p>
  
  <pre><code>def analyze():
      # --Step 1--
      progressbar.grid()
      progressbar.start()
  
      # --Step 2--
      global analysis
      analysis = analyzer.Analysis(file_path.get())
      analysis.output_to_file()
  
      # --Step 3--
      progressbar.stop()
      progressbar.grid_remove()
  </code></pre>
  
  <p>I'd post a picture of my interface to clarify further, but my since my current reputation score does not allow posting of images, I hope I've made the problem clear enough with my explanation (and code).</p>