如何在窗口focus-out-event上退出GtkApplication？

问：

这是 gtk3 中 widget “focus-out-event” 的一个示例。我的目标是在窗口失去焦点时通过单击窗口外退出窗口。但是组合框（子）小部件有问题。每当我单击组合框时，窗口都会失去焦点并关闭。但是，如果我单击缩放小部件，则没问题。这是脚本——

#include <gtk/gtk.h>
//gcc `pkg-config --cflags gtk+-3.0` -o example Changer3.c`pkg-config --libs gtk+-3.0` 

gboolean quit_function (GtkWidget *widget, GdkEvent  *event, gpointer   user_data)
{
    GApplication *app=g_application_get_default();
    g_application_quit(app);
}

static void
activate (GtkApplication *app,
          gpointer        user_data)
{
    //create Window 
    GtkWidget *window;
    GtkWidget *center_vbox;
    GtkWidget *combobox;
    GtkWidget *scale;

    window = gtk_application_window_new (app);
    gtk_window_set_decorated (GTK_WINDOW(window), FALSE);
    gtk_window_set_default_size (GTK_WINDOW(window), 230, 100);
    gtk_widget_set_size_request (window, 230, 100);
    gtk_window_set_title (GTK_WINDOW(window), "config");
    gtk_window_set_resizable (GTK_WINDOW(window), FALSE);
    gtk_window_set_keep_above (GTK_WINDOW(window), TRUE);

    center_vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 2);
    gtk_container_add (GTK_CONTAINER (window), center_vbox);
    combobox = gtk_combo_box_new ();
    gtk_box_pack_start (GTK_BOX (center_vbox), combobox, FALSE, FALSE, 0);

    scale = gtk_scale_new_with_range(GTK_ORIENTATION_HORIZONTAL, 0, 50, 1);
    gtk_box_pack_start (GTK_BOX (center_vbox), scale, TRUE, TRUE, 0);

    //focus-out-event event to auto hide window
    gtk_widget_set_events (window, GDK_FOCUS_CHANGE_MASK);
    g_signal_connect (G_OBJECT(window), "focus-out-event", G_CALLBACK(quit_function), NULL);

    gtk_widget_show_all(window);
}

int
main (int    argc,
  char **argv)
{
  GtkApplication *app;
  int status;

  app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}

我想要这个窗口，这样当我单击任何子小部件（组合框/比例）时，它就不会关闭。但是，如果我单击窗口外的应用程序窗口应该退出。