in tutorials/libguac-client-ball/src/ball.c [155:171]
int ball_free_handler(guac_client* client) {
ball_client_data* data = (ball_client_data*) client->data;
/* Wait for render thread to terminate */
pthread_join(data->render_thread, NULL);
/* Free client-level ball layer */
guac_client_free_layer(client, data->ball);
/* Free client-specific data */
free(data);
/* Data successfully freed */
return 0;
}