title: PyQt QTreeWidget 'expanded' signal not being caught
body: <p>I just started maintaining a set of embedded Python plugins for a Qt application. I'm also new to both PyQt and Python, so bear with me. </p>
  
  <p>I have an implementation of a QTreeWidget in one dialog where the "expanded" signal is not being caught by the corresponding handler. I have another dialog where it works just fine.</p>
  
  <p>In the problem dialog, I can verify that the connect was successful. </p>
  
  <pre><code>connected = wdg.connect(wdg.treeView_,SIGNAL("expanded(QTreeViewItem*)"), wdg.expanded)
  </code></pre>
  
  <p>evaluates to True. When I click on the child indicators to expand an item, the [+] signs change to a minus, but nothing else happens. Likewise, when I click on the [-], it toggles back to [+]. I have set the ChildIndicatorPolicy to initially set the indicator to SHOW in both cases. </p>
  
  <p>In the dialog that works OK, when the user clicks on the plus sign, the 'expanded' handler is executed. Only the indicator toggles when it is clicked.</p>
  
  <p>My handler code is simply:</p>
  
  <pre><code>def expanded(self, item):
      logging.debug("In expanded handler")
  </code></pre>
  
  <p>I have a breakpoint at the logging call, but the statement is never reached.</p>
  
  <p>I the failing dialog, I have another signal that's connected immediately before the one above, and it works just fine:</p>
  
  <pre><code>wdg.connect(wdg.treeView_,SIGNAL("currentItemChanged(QTreeWidgetItem*, QTreeWidgetItem*)"), wdg.itemChanged)
  </code></pre>
  
  <p>Is there anything that could prevent an expanded signal from firing or being caught? Another event perhaps? What should I be looking for? I realize that my nomenclature may be a bit off, and I welcome any correction in that regard as well.</p>