在代理上调用dbus方法不阻塞（或无超时）
我想要锁定我的GNOME屏幕保护程序，但是dbus的.Lock方法在等待回应。我希望它不等待回应（只发送锁定屏幕保护程序的信号，然后继续我的生活）。我该怎么做呢？（实际上这段代码是在一个线程里运行的，所以我可以继续我的生活，但我还是遇到了麻烦的错误）
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
*/