Kivy：从另一个弹出窗口中关闭一个弹出窗口

Question

我kivy.factory.Factory用来打开弹出窗口，但是当我想关闭它们时它不起作用。

代码：

from kivy.app import App

from kivy.lang import Builder

x = Builder.load_string("""

#:import F kivy.factory.Factory

#:import Window kivy.core.window.Window

Screen:

    Button:

        text: 'Press to Open First Popup'

        on_press:

            F.FirstPopup().open()

<FirstPopup@Popup>:

    title: 'First Popup'

    size_hint: None, None

    width: Window.width / 1.4

    height: Window.width / 1.4

    Button:

        text: 'Press to Open Second Popup'

        on_press: F.SecondPopup().open()

<SecondPopup@Popup>:

    title: 'Second Popup'

    size_hint: None, None

    width: Window.width / 1.8

    height: Window.width / 1.8

    Button:

        text: 'Press to Close Both Popups'

        on_press:

            root.dismiss()

            F.FirstPopup().dismiss() # < DOSEN'T WORK

""")

class MyApp(App):

    def build(self):

        return x

MyApp().run()