void
ToggleDucksDial::insert_to_toolbar(Gtk::Toolbar &toolbar, int index)
{
	if (index < 0) index = toolbar.get_n_items();

	// reverse order
	toolbar.insert(ducks_angle,    index);
	toolbar.insert(ducks_width,    index);
	toolbar.insert(ducks_radius,   index);
	toolbar.insert(ducks_tangent,  index);
	toolbar.insert(ducks_vertex,   index);
	toolbar.insert(ducks_position, index);
}