glade aboutDialog没有关闭

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk

class MainWindow(Gtk.Window):
    def __init__(self):
        Gtk.Window.__init__(self, title="Main Window")

        # 创建菜单栏
        menu_bar = Gtk.MenuBar()

        # 创建“关于”菜单项
        menu_item_about = Gtk.MenuItem(label="关于")
        menu_item_about.connect("activate", self.on_about_activate)
        menu_bar.append(menu_item_about)

        # 将菜单栏添加到窗口中
        self.add(menu_bar)

    def on_about_activate(self, widget):
        # 创建aboutDialog对话框
        about_dialog = Gtk.AboutDialog()
        about_dialog.set_program_name("My Application")
        about_dialog.set_version("1.0")
        about_dialog.set_copyright("Copyright © 2021")
        about_dialog.set_comments("这是一个示例程序")

        # 将aboutDialog对话框添加到窗口中
        self.add(about_dialog)

        # 显示aboutDialog对话框
        about_dialog.show()

        # 连接关闭按钮的“clicked”信号到on_about_dialog_close函数
        close_button = about_dialog.get_widget_for_response(Gtk.ResponseType.CLOSE)
        close_button.connect("clicked", self.on_about_dialog_close)

    def on_about_dialog_close(self, widget):
        # 隐藏aboutDialog对话框
        about_dialog.hide()

win = MainWindow()
win.connect("destroy", Gtk.main_quit)
win.show_all()
Gtk.main()