Destroy Qt widgets properly

destroy_qt_widget.py

import sys

from PySide.QtCore import *
from PySide.QtGui import *

@Slot()
def destroy_slot():
    print 'Destroyed'

if __name__ == '__main__':
    #Qt boilerplate
    app = QApplication(sys.argv)

    mw1 = QMainWindow()
    mw2 = QMainWindow()
    w = QWidget(mw1)

    w.destroyed.connect(destroy_slot)
    mw1.destroyed.connect(destroy_slot)
    mw2.destroyed.connect(destroy_slot)

    mw1.show()
    mw2.show()

    app.exec_()

    #Uncomment this to destroy Qt widgets properly
    #del mw1
    #del mw2

    sys.exit()