I need to implement a function that monitors the screen lock/unlock. I referred to the following article:Run script on screen lock/unlockMy python script code works fine in Ubuntu 12.04, but it doesn't work in Ubuntu 14.04:  #!/usr/bin/env python  import gobject  import dbus  from dbus.mainloop.glib import DBusGMainLoop  def filter_cb(bus, message):    if message.get_member() != ActiveChanged:        return    args = message.get_args_list()    if args[0] == True:        print(Lock Screen)    else:        print(Unlock Screen)DBusGMainLoop(set_as_default=True)bus = dbus.SessionBus()bus.add_match_string(type='signal',interface='org.gnome.ScreenSaver')bus.add_message_filter(filter_cb)mainloop = gobject.MainLoop()mainloop.run()I also tried the command:dbus-monitor --session interface='org.gnome.ScreenSaver'  It outputs nothing when I lock/unlock the screen manually.How can I monitor the screen lock/unlock in the Ubuntu 14.04?
How to monitor the screen lock/unlock in the Ubuntu 14.04
ubuntu;python;d bus