Quite interested to know that too.. Not only for refresh, for reboot and for shutdown as well. I know there are apps for that (did i just say that?), but it would be interesting to know exactly how it works..how would we be able to get a desktop shortcut for a terminal command (as root).
/sbin/reboot
/sbin/initctl restart xsession/sysuid
/sbin/initctl restart xsession/mthome