g_signal_connect(G_OBJECT(win), "delete-event", G_CALLBACK(on_delete), NULL);
g_signal_connect(G_OBJECT(win), "destroy", G_CALLBACK(on_destroy), NULL);
main_window = win;
g_signal_connect(G_OBJECT(win), "delete-event", G_CALLBACK(on_delete), NULL);
g_signal_connect(G_OBJECT(win), "destroy", G_CALLBACK(on_destroy), NULL);
main_window = win;