title: Edit a Widget in Kv
body: <p>I have a widget that I defined in Kv language, which exists within a layout that I also defined in Kv language. I would like to change the text of the widget in the layout in Kv. How would I go about is?</p>
  
  <p>Python code:</p>
  
  <pre><code>import kivy
  kivy.require('1.11.1')
  from kivy.app import App
  from kivy.uix.boxlayout import BoxLayout
  
  
  class Test(BoxLayout):
      pass
  
  
  class KivyTestApp(App):
      def build(self):
          return Test()
  
  
  app = KivyTestApp()
  app.run()
  </code></pre>
  
  <p>Kv code:</p>
  
  <pre><code>&lt;Header@BoxLayout&gt;:
      orientation: 'horizontal'
      size_hint_y: 0.2
  
      Button:
          text: 'Button 1'
      Button:
          id: edit_but
  
  &lt;Test&gt;:
      orientation: 'vertical'
  
      Header:
          edit_but.text: 'Button 2'
          # How do I do this ^ ?
      Label:
          text: 'Filler'
  
  </code></pre>