[balsa/wip/gtk4] main-window: On 'quit', use gtk_window_close()

[Peter Bloomfield <peterb src gnome org>]

commit 10aaa4b241fbe50866779273d7a09f64846e9b00
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Sun Jun 10 23:17:55 2018 -0400

    main-window: On 'quit', use gtk_window_close()
    
    not gtk_widget_destroy(). That way, a compose-window with unsaved changes
    can again block quitting to ask the user what to do with the changes.

 src/main-window.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/main-window.c b/src/main-window.c
index 2f9bcf5d..7b90c03d 100644
--- a/src/main-window.c
+++ b/src/main-window.c
@@ -1039,7 +1039,7 @@ quit_activated(GSimpleAction * action,
     while(gtk_events_pending())
         gtk_main_iteration_do(FALSE);
 
-    gtk_widget_destroy((GtkWidget *) window);
+    gtk_window_close(window);
 }
 
 static void