Can't properly pass "user_data" to callback for open file dialog about cl-gtk4 HOT 2 CLOSED

;;;; package.lisp

(defpackage #:iip-project
  (:use #:cl))

;;;; iip-project.lisp

(in-package #:iip-project)

(gtk:define-application (:name iip-project
                         :id "org.kayprish.iip-project")
  (cffi:defcallback open-file-callback :void ((file-dialog :pointer)
                                              (result :pointer)
                                              ; data now contains (img-original img-new)
                                              (data :pointer))
    (setf file-dialog (gobj:pointer-object file-dialog 'gtk:file-dialog))
    (setf data        (glib::get-object (cffi:pointer-address data)))
    (funcall
      (gtk::attach-restarts
        (lambda ()
          (alexandria:when-let ((img-original (first data))
                                (img-new      (second data))
                                (gfile        (ignore-errors
                                                (gtk:file-dialog-open-finish file-dialog result))))
            ; here do something with img-original and img-new
            )))))

  (gtk:define-main-window (window (gtk:make-application-window :application gtk:*application*))
    (let ((grid         (gtk:make-grid))
          (file-button  (gtk:make-button :label "Load file"))
          (img-original (gtk:make-image))
          (img-new      (gtk:make-image)))

      (gtk:connect file-button "clicked"
                   (lambda (button)
                     (let ((file-chooser  (gtk:make-file-dialog)))
                       (gtk:file-dialog-open file-chooser
                                             window
                                             nil
                                             (cffi:callback open-file-callback)
                                             ;;; THE FOLLOWING LINE CAUSES THE ERROR
                                             (cffi:make-pointer (glib::put-object (list img-original img-new)))))))

      (setf (gtk:window-child window) grid)

      (gtk:grid-attach grid img-original 0 1 1 1)
      (gtk:grid-attach grid file-button 0 2 1 1)

      (gtk:grid-attach grid img-new 2 1 1 1))
    (unless (gtk:widget-visible-p window)
      (gtk:window-present window))))