Kivy: Android settings style tablet panes

tablettest.py

import kivy
kivy.require('1.8.1')

from kivy.app import App
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.floatlayout import FloatLayout


class PageList(BoxLayout):
	target_sm = ObjectProperty()
	
	def switch(self, page):
		self.target_sm.current = page


Builder.load_string('''
<PageList>
	orientation: 'vertical'
	Button:
		text: 'Page 1'
		on_release: root.switch('page1')
	Button:
		text: 'Page 2'
		on_release: root.switch('page2')

<BlankPage@Screen>:
	name: 'blankpage'

<Page1@Screen>:
	name: 'page1'
	Label:
		text: 'Page 1'

<Page2@Screen>:
	name: 'page2'
	Label:
		text: 'Page 2'
''')


root1 = Builder.load_string('''
BoxLayout:
	orientation: 'vertical'
	
	ScreenManager:
		id: sm
		Screen:
			name: 'pagelist'
			PageList:
				target_sm: sm
		Page1
		Page2
	
	Button:
		text: 'Back'
		on_release: sm.current = 'pagelist'
		size_hint_y: None
		height: 0 if self.disabled else dp(64)
		opacity: 0 if self.disabled else 1
		disabled: sm.current == 'pagelist'
''')

root2 = Builder.load_string('''
BoxLayout:
	PageList:
		target_sm: sm
	ScreenManager:
		id: sm
		BlankPage
		Page1
		Page2
''')


class Container(FloatLayout):
	def on_size(self, *args):
		if self.width > self.height:
			if root2 not in self.children:
				self.clear_widgets()
				self.add_widget(root2)
		elif root1 not in self.children:
			self.clear_widgets()
			self.add_widget(root1)


class TestApp(App):
	def build(self):
		return Container()


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