title: Kivy Custom Button Text
body: <p>What is the best way to add text to a custom button, from the python-side? Here is my code so far:</p>
  
  <pre><code>class CircularButton(ButtonBehavior, Widget):
  
          # code inspired from:
          # https://github.com/kivy/kivy/issues/4263#issuecomment-217430358
          # https://stackoverflow.com/a/42886979/6924364
          # https://blog.kivy.org/2014/10/updating-canvas-instructions-declared-in-python/
  
      def __init__(self, **kwargs):
          super(CircularButton,self).__init__(**kwargs)
  
          self.add_widget(Label(text='test')) # &lt;-- put this in the middle of the button
  
          with self.canvas:
              Color(rgba=(.5,.5,.5,.5))
              self.shape = Ellipse(pos=self.pos,size=self.size)
  
          self.bind(pos=self.update_shape, size=self.update_shape)
  
      def update_shape(self, *args):
          self.shape.pos = self.pos
          self.shape.size = self.size
  
      def collide_point(self, x, y):
          return Vector(x, y).distance(self.center) &lt;= self.width / 2
  </code></pre>
  
  <p>When linked to a widget in the .kv file, you see that the 'text' label appears at (0,0) rather than on top of the button. What is the best way to set the text for this custom button?</p>