Add ag_app_buttoned_dialog() to ag-app.h

src/ag-app.h

@@ -47,6 +47,11 @@ void ag_app_run_action(AgApp                   *app,
                        gboolean                is_remote,
                        const AstrognomeOptions *options);
 
+gint ag_app_buttoned_dialog(GtkWidget      *window,
+                            GtkMessageType message_type,
+                            const gchar    *message,
+                            const gchar    *first_button_text, ...);
+
 void ag_app_message_dialog(GtkWidget      *window,
                            GtkMessageType message_type,
                            gchar          *fmt, ...);