old_contents: from kivy.app import App
  from kivy.lang import Builder
  from kivy.properties import ConfigParserProperty
  
  KV = '''
  FloatLayout:
      BoxLayout:
          size_hint: .5, .5
          pos_hint: {'center': (.5, .5)}
  
          orientation: 'vertical'
  
          TextInput:
              text: app.text
              on_text: app.text = self.text
  
          Slider:
              min: 0
              max: 100
              value: app.number
              on_value: app.number = self.value
  '''
  
  
  class ConfigApp(App):
      number = ConfigParserProperty(0, 'general', 'number', 'app', val_type=float)
      text = ConfigParserProperty('', 'general', 'text', 'app', val_type=str)
  
      def build_config(self, config):
          config.setdefaults(
              'general',
              {
                  'number': 0,
                  'text': 'test'
              }
          )
  
      def build(self):
          return Builder.load_string(KV)
  
  
  if __name__ == '__main__':
      ConfigApp().run()
  
new_contents: from kivy.app import App
  from kivy.lang import Builder
  from kivy.properties import ConfigParserProperty
  
  KV = '''
  FloatLayout:
      BoxLayout:
          size_hint: .5, .5
          pos_hint: {'center': (.5, .5)}
  
          orientation: 'vertical'
  
          TextInput:
              text: app.text
              on_text: app.text = self.text
  
          Slider:
              min: 0
              max: 100
              value: app.number
              on_value: app.number = self.value
  '''
  
  
  class ConfigApp(App):
      number = ConfigParserProperty(
          0, 'general', 'number',
          'app', val_type=float
      )
      text = ConfigParserProperty(
          '', 'general', 'text',
          'app', val_type=str
      )
  
      def build_config(self, config):
          config.setdefaults(
              'general',
              {
                  'number': 0,
                  'text': 'test'
              }
          )
  
      def build(self):
          return Builder.load_string(KV)
  
  
  if __name__ == '__main__':
      ConfigApp().run()
  
subject: Fix PEP8 in app_with_config.py