mode_tree_key
int mode_tree_key(struct mode_tree_data *, struct client *, key_code *,
finished = mode_tree_key(mtd, c, &key, m, NULL, NULL);
finished = mode_tree_key(mtd, c, &key, m, NULL, NULL);
finished = mode_tree_key(data->data, c, &key, m, NULL, NULL);
finished = mode_tree_key(data->data, c, &key, m, &x, &y);