问如何正确对齐基维中的TabbedPanel选项卡

EN

import kivy
kivy.require('2.0.0')

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.tabbedpanel import TabbedPanel


class Main(TabbedPanel):
    pass


class MyApp(App):

    def build(self):
        return  Main()


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

<Main>
    tab_width: self.content.width / 3
    do_default_tab: False
    padding: (5, 5)
    TabbedPanelItem:
        text: 'First Tab'
    TabbedPanelItem:
        text: 'Second Tab'
    TabbedPanelItem:
        text: 'Third Tab'