Add 'suspend the computer' to logout dialogue?

[leon <sdl.web@googlemail.com>]

Hi there,

I'd like to configure the logout dialogue in gnome to look like this:

                        * Log out
                        * Suspend the computer
                        * Shutdown
                        * Restart the computer

By the way, how can gnome execute 'Suspend the computer' which
normally needs root privilege?

Many thanks.

Leon