title: QPropertyAnimation doesn't work with a child widget
body: <p>The below code doesn't animate the button as expected. But it works if the button is stand alone and stops working when it is a child widget. What am I doing wrong here?</p>
  
  <p>I'm trying this on Ubuntu.</p>
  
  <pre><code>class TestWindow(QtGui.QWidget):
  
      def __init__(self):
          QtGui.QWidget.__init__(self)
  
          self.button = QtGui.QPushButton("Ok")
          self.button.setParent(self)
          self.button.setGeometry(QtCore.QRect(0,0,50,50))
          self.button.clicked.connect(self.anim)
  
      def anim(self):
  
          animation = QtCore.QPropertyAnimation(self.button, "geometry")
          animation.setDuration(10000)
          animation.setStartValue(QtCore.QRect(0,0,0,0))
          animation.setEndValue(QtCore.QRect(0,0,200,200))
          animation.start()
  
  if __name__ == '__main__':
          app = QtGui.QApplication(sys.argv)
  
          r = TestWindow()
          r.show()
  
          sys.exit(app.exec_())
  </code></pre>