RST.py

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.button import Button


class RSTApp(App):
    pass

class MyButton(Button):

    def change_text1(self):
        textfield = self.ids['rsttext1']
        textfield.text = "whatever"

    def change_text2(self):
        textfield = self.ids['rsttext2']
        textfield.text = "whatever"


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