title: Label not affected by AnchorLayout - Kivy
body: <p>I have just started learning kivy and am stuck with this layout problem.
  I used the Anchor Layout to center a button using:</p>
  
  <p><code>Button:
      text: "A button"
      anchor_x:'center'
      anchor_y:'center'</code></p>
  
  <p>However when I try this:</p>
  
  <pre><code>Label:
      text: "Hello World!"
      size_hint: 1, 1
      anchor_x:'center'
      anchor_y:'top'
  </code></pre>
  
  <p>It just shows "Hello World!" in the default center position but I want it above my centered button.</p>
  
  <p>I have tried everything and looked at the docs but have found nothing to explain this.</p>
  
  <p>Edit:
  Here are both files:</p>
  
  <p>py file:</p>
  
  <pre><code>import kivy
  kivy.require('1.8.0')
  
  from kivy.app import App
  from kivy.uix.anchorlayout import AnchorLayout
  
  class Layout(AnchorLayout):
      pass
  
  class LayoutApp(App):
      def build(self):
          return Layout()
  
  if __name__ == '__main__':
      LayoutApp().run()
  </code></pre>
  
  <p>kv file:</p>
  
  <pre><code>&lt;Layout&gt;:
      Label:
          text: "Hello World!"
          font_size: 50
          size_hint: None, None
          height: 100
          anchor_x:'center'
          anchor_y:'top'
  
      Button:
          text: "Button"
          background_colour: (0,0,1,1)
          size_hint: None, None
          size: 50, 50
          anchor_x:'center'
          anchor_y:'top'
  </code></pre>