Application name in kivy

Question

I have two applications with one kv file. Between both applications is different only in app class name. Application A gives good result, but application B is bad. Where is problem?

application A:

import kivy
kivy.require('1.0.5')
from kivy.lang.builder import Builder

from kivy.uix.button import Button
from kivy.uix.gridlayout import GridLayout
from kivy.app import App

class MyW(GridLayout):
    pass

class ShowApp(App):
def build(self):
    Builder.load_file('d:\\MyPgm\\Python\\kivy\\ControlShow    \\ControlShow.kv')
    return MyW()


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

application B:

import kivy
kivy.require('1.0.5')
from kivy.lang.builder import Builder

from kivy.uix.button import Button
from kivy.uix.gridlayout import GridLayout
from kivy.app import App

class MyW(GridLayout):
    pass

class ControlShowApp(App):
def build(self):
    Builder.load_file('d:\\MyPgm\\Python\\kivy\\ControlShow    \\ControlShow.kv')
    return MyW()


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

KV file:

<MyW>
    cols: 2
    rows: 2
    Button:
      id: label1
      text: 'B1'
    Button:
      id: label2
      text: 'B2'
    Button:
      id: label3
      text: 'B3'
    Button:
      id: label4
      text: 'B4'

Answer 1

The problems are as follow:

1. A class rule, declared by the name of a widget class between < > and followed by : e.g. <MyW>:
2. The indentation is 4 spaces

Example

ControlShow.kv

#:kivy 1.10.0

<MyW>:
    cols: 2
    rows: 2
    Button:
        id: label1
        text: 'B1'
    Button:
        id: label2
        text: 'B2'
    Button:
        id: label3
        text: 'B3'
    Button:
        id: label4
        text: 'B4'

ShowApp.py

from kivy.lang.builder import Builder
from kivy.uix.gridlayout import GridLayout
from kivy.app import App


class MyW(GridLayout):
    pass


class ShowApp(App):
    def build(self):
        Builder.load_file('d:\\MyPgm\\Python\\kivy\\ControlShow    \\ControlShow.kv')
        return MyW()


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

ControlShowApp.py

from kivy.lang.builder import Builder
from kivy.uix.gridlayout import GridLayout
from kivy.app import App


class MyW(GridLayout):
    pass


class ControlShowApp(App):
    def build(self):
        Builder.load_file('d:\\MyPgm\\Python\\kivy\\ControlShow    \\ControlShow.kv')
        return MyW()


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

Output