map_coords_to_ancestor(rx, ry, *find_ancestor<GLtk::Root>());
Ray ray = engineer.get_main_view().create_ray(rx, ry);
Track *track = engineer.get_layout().pick<Track>(ray);
map_coords_to_ancestor(rx, ry, *find_ancestor<GLtk::Root>());
Ray ray = engineer.get_main_view().create_ray(rx, ry);
Track *track = engineer.get_layout().pick<Track>(ray);