hello.py

import kivy

from kivy.clock import Clock 
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
 
def on_enter(instance):
    print '============== still in "global?" on_enter() ===================='
    print 'User pressed enter in', instance # Python 3 way: print('User pressed enter in', instance)
    print '"value" == ', instance.text # Python 3 way: print('"value" == ', instance.text)
    print 'resetting focus BACK to textinput!'
    # self.focus = True # error:  NameError: global name 'self' is not defined
 
class MyTextInput(TextInput):
    def on_parent(self, widget, parent):
        self.focus = True
 
    def set_focus(self):
        self.focus = True

    def on_enter(self, value):
        # import pdb; pdb.set_trace()
        global myApp
        myApp.label.text += ("\n"+value.text)
        self.text = ''
        # print 'User pressed enter in', instance # Python 3 way: print('User pressed enter in', instance)
        # print '"value" == ', instance.text # Python 3 way: print('"value" == ', instance.text)
        # print 'resetting focus BACK to textinput!'
        Clock.schedule_once(lambda dt: self.set_focus())
        # instance.focus = True
 
class BoundedLabel(Label):
    pass
 
class MyApp(App):
 
    def build(self):
        self.root = FloatLayout(padding=10)
        self.label = BoundedLabel(text='Hello world', halign="left", valign="top") # text_size: self.size # halign: 'right' # valign: 'middle'
        self.label.bind(size=self.label.setter('text_size'))
        self.root.add_widget(self.label)
        # textinput = TextInput(size_hint=(self.root.width, None), size=(100, 50), multiline=False) # , focus=True) locked up app!
        textinput = MyTextInput(size_hint=(self.root.width, None), size=(100, 50), multiline=False) # , focus=True) locked up app!
        textinput.bind(on_text_validate=textinput.on_enter)
        self.root.add_widget(textinput)
        return self.root

 
if __name__ == '__main__':

    global myApp
    myApp = MyApp()
    myApp.run()