def build(self): Window.size = (500, 300) # Window.borderless = True sm = ScreenManager() screens = [ MenuScreen(name='menu'), SettingsScreen(name='settings') ] sm.add_widget(screens[0]) sm.add_widget(screens[1]) sm.transition = SwapTransition() sm.current_screen = screens[0] # # later # sm.switch_to(screens[1], direction='right') return sm