The --gui option will report errors in dialog boxes instead of printing to stderr.
If called with the --logout option, the current GNOME session will be ended, unless logging out has been inhibited by an application. The --force-logout option can be used to end the session regardless of the inhibition state.
When the --logout-dialog option is given, the standard dialog displaying logout options is displayed. When --shutdown-dialog option is given, the standard dialog displaying shutdown options is displayed.
The --kill and --silent options are deprecated. The --kill option is equivalent to the --logout-dialog option. If --silent is used with --kill, then it will behave as if --logout was used.
The session is not saved when gnome-session-save is called with any of the options ending the session.