(In reply to comment #1)
> When I'm monitoring my dbus socket, it showed as:
> $ dbus-monitor --address unix:path=/var/run/dbus/system_bus_socket --monitor
When you are the only user logged in, there should usually be two dbus-daemon processes. One is the system bus (runs as user messagebus, listens on /var/run/dbus/system_bus_socket) and the other is the session bus (runs as your own user ID, listens on some address involving /tmp which you can get from the $DBUS_SESSION_BUS_ADDRESS environment variable). If you debug the wrong one, the results aren't likely to be very useful.
(In reply to comment #1) /var/run/ dbus/system_ bus_socket --monitor
> When I'm monitoring my dbus socket, it showed as:
> $ dbus-monitor --address unix:path=
When you are the only user logged in, there should usually be two dbus-daemon processes. One is the system bus (runs as user messagebus, listens on /var/run/ dbus/system_ bus_socket) and the other is the session bus (runs as your own user ID, listens on some address involving /tmp which you can get from the $DBUS_SESSION_ BUS_ADDRESS environment variable). If you debug the wrong one, the results aren't likely to be very useful.
> Destination is NULL, it's normal?
Yes, broadcast signals have a null destination.