default policy

[Bear]

hi,
There looks like that something was wrong on my system. It seems that dbus stop transferring so many messages. For example, if I run this command as a normal user(not root):
dbus-send --session --dest='org.gnome.SessionManager' --print-reply --type=method_call /org/gnome/SessionManager org.gnome.SessionManager.CanShutdown

It would responsed nothing. Even if a normal user have no right to shutdown, it should return a 'refuse' message. 
Could you tell me why this happen?
thx!!

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Bear
2010-07-30