如何在不按任何按钮的情况下在kivy中显示对话框？

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from kivy.clock import Clock

class MyLayout(BoxLayout):
    def __init__(self, **kwargs):
        super(MyLayout, self).__init__(**kwargs)
        # 设置一个定时器，在5秒后显示对话框
        Clock.schedule_once(self.show_popup, 5)

    def show_popup(self, dt):
        # 创建对话框内容
        content = Label(text='这是一个自动弹出的对话框')
        # 创建对话框
        popup = Popup(title='自动弹出', content=content, size_hint=(None, None), size=(400, 400))
        # 打开对话框
        popup.open()

class MyApp(App):
    def build(self):
        return MyLayout()

if __name__ == '__main__':
    MyApp().run()