Kivy在FloatLayout中移动标签

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.widget import Widget
from kivy.properties import NumericProperty
from kivy.core.window import Window

class MyFloatLayout(FloatLayout):
    pass

class MyFloatLayout(FloatLayout):
    def __init__(self, **kwargs):
        super(MyFloatLayout, self).__init__(**kwargs)
        
        self.label = Label(text='Hello, Kivy!', pos=(100, 100))
        self.add_widget(self.label)
        
        self.button = Button(text='Move Label', pos=(200, 200))
        self.button.bind(on_release=self.move_label)
        self.add_widget(self.button)
        
    def move_label(self, *args):
        self.label.pos = (300, 300)

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

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