cellrenderer_time_track->signal_waypoint_changed().connect(sigc::mem_fun(*this, &TimeTrackView::on_waypoint_changed) );
column->add_attribute(cellrenderer_time_track->property_value_desc(), model.value_desc);
column->add_attribute(cellrenderer_time_track->property_canvas(), model.canvas);
cellrenderer_time_track->signal_waypoint_changed().connect(sigc::mem_fun(*this, &TimeTrackView::on_waypoint_changed) );
column->add_attribute(cellrenderer_time_track->property_value_desc(), model.value_desc);
column->add_attribute(cellrenderer_time_track->property_canvas(), model.canvas);