from kivy.app import App
from kivy.graphics import Ellipse, Line
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput

class CustomLayout(BoxLayout):

	def __init__(self, **kwargs):
		super(CustomLayout, self).__init__(**kwargs)
		with self.canvas.after:
			pass
		self.textinput = TextInput(text='Hello world', multiline=False)
		self.add_widget(self.textinput)
		self.textinput.bind(on_text_validate=self.on_enter)

	def on_enter(self,instance, value):
		print('User pressed enter in', instance)

	


class MainApp(App):

	def build(self):
		root = CustomLayout()
		return root

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