Hybernate on CentOS5.1

Found a way to hybernate (suspend to disk) through the xfce (and gnome) interface on CentOS5.1.
I don't see the hybernate button on the quit form (there only Logout, Restart and Shutdown).

Started

 gnome-power-preferences 

and made settings:


Then got the icon in the tray through which it is possible to hybernate: