//g_signal_connect(drawing, "expose-event", G_CALLBACK(expose), NULL);
g_signal_connect (drawing, "expose-event", G_CALLBACK(expose_start), NULL);
g_signal_connect_after(drawing, "expose-event", G_CALLBACK(expose_end), NULL);
//g_signal_connect(drawing, "expose-event", G_CALLBACK(expose), NULL);
g_signal_connect (drawing, "expose-event", G_CALLBACK(expose_start), NULL);
g_signal_connect_after(drawing, "expose-event", G_CALLBACK(expose_end), NULL);