Gtk::Widget::signal_delete_event ()

[Phil Wolff <adiabat hughes net>]

Documentation says "The default handler for this signal destroys the 
window. Connecting Gtk::Widget::hide_on_delete() to this signal will 
cause the window to be hidden instead, so that it can later be shown 
again without reconstructing it."

This is exactly the behavior I want, but g++ says "error: 
‘hide_on_delete’ is not a member of ‘Gtk::Widget’".

What am I missing?