g_signal_connect(window, "delete-event", G_CALLBACK(on_delete), NULL);
gtk_window_add_accel_group(GTK_WINDOW(window),
gtk_ui_manager_get_accel_group(manager));
+ gtk_widget_set_size_request(GTK_WIDGET(viewer), 400, 300);
*_notebook = notebook;
return window;
}