+ g_signal_connect_after(opengl, "key-press-event", G_CALLBACK(on_chained_event), NULL);
+ g_signal_connect_after(opengl, "key-release-event", G_CALLBACK(on_chained_event), NULL);
+ g_signal_connect_after(opengl, "button-press-event", G_CALLBACK(on_chained_event), NULL);
+ g_signal_connect_after(opengl, "button-release-event", G_CALLBACK(on_chained_event), NULL);
+ g_signal_connect_after(opengl, "motion-notify-event", G_CALLBACK(on_chained_event), NULL);
+