title: pyside widget.show not blocking
body: <p>I wrote a little application, that saves small videos it generates. The code pasted should do the following:</p>
  
  <ol>
  <li>show  dialog to the user to choose a directory</li>
  <li>if directory is not empty show widget that has a circle running around so there's a feedback that something is going on</li>
  <li>then generate the movies (which takes some time and most if it has handled with multiprocessing pool)</li>
  <li>(not included in snippet, but the code would go on to do more background stuff, so the loading widget would stay on for a while</li>
  </ol>
  
  <p>Code:</p>
  
  <pre><code>def saveMovie(self):
      self.pause()
  
      if not os.path.exists("outputs"):
          os.makedirs("outputs")
      dir = QtGui.QFileDialog.getExistingDirectory(self,dir="outputs",options=QtGui.QFileDialog.ShowDirsOnly)
  
      if not dir == '':
          self.loading = True
          self.loadingWidget.show()
          name = os.path.basename(dir) + "_"
          settings = sm.fetch_settings()
          swarms,l,l1,l2 = self.generate_movies()
  </code></pre>
  
  <p>Now instead of this, what happens is that the dialog disappears and the loading widget is shown only after the program has existed from <code>self.generate_movies()</code>. What am I missing?</p>