title: Is this PyQt 4 python bug or wrongly behaving code?
body: <p>Following code should create the QGraphicsView widget which owns one QGraphicsScene having text inside of it:</p>
  
  <pre><code>#!/usr/bin/python
  
  import sys
  from PyQt4.QtGui import *
  
  
  if __name__ == '__main__':
    app = QApplication(sys.argv)
  
    view = QGraphicsView()  
    scene = QGraphicsScene()
  
    scene.addText("Hello!")
  
    view.setScene(scene)
    view.show();
  
    sys.exit(app.exec_())
  </code></pre>
  
  <p>This opens the window, puts the text there, but after I close window - python dumps core and several issues are printed out:</p>
  
  <pre><code>(python:5387): Gtk-CRITICAL **: IA__gtk_container_add: assertion `GTK_IS_CONTAINER (container)' failed
  
  (python:5387): Gtk-CRITICAL **: IA__gtk_widget_realize: assertion `GTK_WIDGET_ANCHORED (widget) || GTK_IS_INVISIBLE (widget)' failed
  ...clip...
  ... above message is shown many, many times ...
  ...clip...
  (python:5387): Gtk-CRITICAL **: IA__gtk_widget_realize: assertion `GTK_WIDGET_ANCHORED (widget) || GTK_IS_INVISIBLE (widget)' failed
  Segmentation fault (core dumped)
  </code></pre>
  
  <p>Versions:
  python2.7                              2.7.3-0ubuntu3.1
  python-qt4                             4.9.1-2ubuntu1</p>