Sets the update policy for the range. Gtk::UPDATE_CONTINUOUS means that anytime the range slider is moved, the range value will change and the value_changed signal will be emitted. Gtk::UPDATE_DELAYED means that the value will be updated after a brief timeout where no slider motion occurs, so updates are spaced by a short time rather than continuous. Gtk::UPDATE_DISCONTINUOUS means that the value will only be updated when the user releases the button and ends the slider drag operation.
See also: get_update_policy()