How to hibernate?

[Stefano Facchini <stefano facchini gmail com>]

Hi,

how can I hibernate (aka suspend-to-disk) my laptop? Closing the lid 
just causes the system to suspend-to-ram (which is the behavior I want), 
while the power button only offers the possibility to turn off the 
computer, so where is hibernation (letting aside typing something in the 
terminal)? Or maybe I am missing something in building gnome-shell..