Kivy (安卓)：ScrollView.scroll_to()没有显示被键盘隐藏的小部件

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.scrollview import ScrollView
from kivy.uix.label import Label
from kivy.core.window import Window
from kivy.lang import Builder

Builder.load_string('''
<MainLayout>:
    orientation: 'vertical'
    ScrollView:
        id: scroll_view
        BoxLayout:
            id: container
            orientation: 'vertical'
            size_hint_y: None
            height: self.minimum_height
            Label:
                text: 'This is a hidden widget'
                size_hint_y: None
                height: '48dp'
            Label:
                text: 'This is another hidden widget'
                size_hint_y: None
                height: '48dp'
    TextInput:
        on_focus: root.on_textinput_focus(self, self.focus)
''')

class MainLayout(BoxLayout):
    def on_textinput_focus(self, instance, focused):
        if focused:
            # 键盘弹出时，调整ScrollView的高度
            Window.softinput_mode = 'resize'
        else:
            # 键盘隐藏时，恢复ScrollView的高度
            Window.softinput_mode = 'pan'

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

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