The update policy of a Range widget defines at what points during user interaction it will change the value field of its Gtk::Adjustment and emit the valuechanged signal. The update policies, set with the set_update_policy() method, are:
Gtk::UPDATECONTINUOUS - This is the default. The valuechanged signal is emitted continuously, i.e. whenever the slider is moved by even the tiniest amount.
Gtk::UPDATEDISCONTINUOUS - The valuechanged signal is only emitted once the slider has stopped moving and the user has released the mouse button.
Gtk::UPDATEDELAYED - The valuechanged signal is emitted when the user releases the mouse button, or if the slider stops moving for a short period of time.