def handler(self):
    'Handler on explicitly closing the GUI window.'
    self.pauseMovie()
    if messagebox.askokcancel('Quit?', 'Are you sure you want to quit?'):
        self.exitClient()
    else:
        self.playMovie()
Handler on explicitly closing the GUI window.
def handler(self):
    
    self.pauseMovie()
    if messagebox.askokcancel('Quit?', 'Are you sure you want to quit?'):
        self.exitClient()
    else:
        self.playMovie()