title: PySide : Children objects not destroyed on close of parent object
body: <p>I have the following code :</p>
  
  <pre><code>import sys
  from PySide import QtGui
  from PySide import QtCore
  
  class Main_Window(QtGui.QMainWindow):
      def __init__(self):
          super(Main_Window,self).__init__()
          self.initUI()
  
      def initUI(self):
          self.navigateur=QtGui.QMdiArea()
          self.setCentralWidget(self.navigateur)
          self.setGeometry(50, 50, 600, 600)
          self.window =QtGui.QWidget(None,QtCore.Qt.WA_DeleteOnClose)
          self.window.grid=QtGui.QGridLayout()
          self.window.button=QtGui.QPushButton("quit",parent=self.window)
          self.window.button.setObjectName("test")
          self.window.button.clicked.connect(self.try_close)
          self.window.grid.addWidget(self.window.button)
          self.window.setLayout(self.window.grid)
          self.window.setFixedSize(self.window.sizeHint())
          self.fwindow=self.navigateur.addSubWindow(self.window,QtCore.Qt.WA_DeleteOnClose)
          self.show()
  
      def try_close(self):
          self.fwindow.close()
          print(self.window.findChild(QtGui.QPushButton,"test"))
  
  def main():
      app=QtGui.QApplication(sys.argv)
      main_wdw=Main_Window()
      sys.exit(app.exec_())
  
  if __name__=="__main__":
      main()
  </code></pre>
  
  <p>According to the documentation, when I close self.window, all children of self.window should be deleted however it doesn't seem to be the case since the print function prints something like PySide.QtGui.QPushButton object at...</p>
  
  <p>What is going wrong ?</p>