Problems when trying to handle GTK's OPEN signal about cl-gtk4 HOT 2 CLOSED

(defpackage test-application-open
  (:use #:cl #:gtk4))

(in-package #:test-application-open)

(defun main ()
  (let ((app (make-application :application-id "org.bohonghuang.test-application-open"
                               :flags gio:+application-flags-handles-open+)))
    (connect app "activate" (lambda (app)
                              (gio:application-open app (list (gio:file-new-for-path "/home/coco24/.emacs.d/init.el")
                                                              (gio:file-new-for-path "/home/coco24/.emacs.d/local.el"))
                                                    "")))
    (connect app "open" (lambda (app files n-files hint)
                          (declare (ignore app hint))
                          (let ((files (loop :for i :below n-files
                                             :collect (make-instance 'gir::object-instance
                                                                     :class (gir:nget gio:*ns* "File")
                                                                     :this (cffi:mem-aref files :pointer i)))))
                            (print (mapcar #'gio:file-basename files))))) ;; This outputs ("init.el" "local.el")
    (gio:application-run app nil)))