example

from kivy.uix.button import Button 
from kivy.uix.pagelayout import PageLayout 
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.stencilview import StencilView 
from kivy.lang import Builder
from kivy.uix.scrollview import ScrollView
from kivy.app import App
from kivy.animation import Animation
from kivy.animation import AnimationTransition
from kivy.uix.label import Label
Builder.load_string(
'''
<TransitionWidget>:
	border: '0dp'
	page: 1
	Button:
		id: 'head'
		text: "hello"


	BoxLayout:
		ScrollView:
			bar_color: 1, 0 , 0, 1
			bar_width: 4
			Label:
		        text: 'my name is Yash '*100
		        font_size: 50
		        text_size: self.width, None
		        size_hint_y: None
		        height: self.texture_size[1]
		        
		        # on_scroll_start: root.anime()
		        
		        AnchorLayout:
		        	size: self.parent.size
		        	pos: self.parent.pos
		        	anchor_x: 'right'
		        	anchor_y: 'top'
		        	Button:
		        		id: cross
		        		size_hint: None, None
		        		height: '60dp'
		        		width: '60dp'
		        		on_press: root.page = 0
		        		background_color: 0, 0.99, 0.59, 1
''')


class TransitionWidget(PageLayout):
	def anime(self):
		print "hello yash"
class ScreenApp(App):

	def build(self):
		return	TransitionWidget()
ScreenApp().run()