call dbus method on proxy without blocking (or no timeout)

I'm trying to lock my GNOME screensaver, however the dbus .Lock method is waiting for a response. I would like it to not wait for a response (just send the signal to lock the screensaver, and continue on with life). How do I do this? (In practice this code is in a thread so I cont开发者_开发技巧inue on with life, but I still get the nasty error)

session_bus = dbus.SessionBus()                                                                                                                                       
screensaver_proxy = session_bus.get_object('org.gnome.ScreenSaver', '/org/gnome/ScreenSaver')                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
locked = screensaver_proxy.Lock(dbus_interface='org.gnome.ScreenSaver')
print "HELLO" # will never get called, due to:
/*
  locked = screensaver_proxy.Lock(dbus_interface='org.gnome.ScreenSaver')
  File "/usr/lib/pymodules/python2.6/dbus/proxies.py", line 68, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/pymodules/python2.6/dbus/proxies.py", line 140, in __call__
    **keywords)
  File "/usr/lib/pymodules/python2.6/dbus/connection.py", line 620, in call_blocking
    message, timeout)
  DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken
*/

Bah. Solution: http://dbus.freedesktop.org/doc/dbus-python/doc/tutorial.html#making-asynchronous-method-calls