title: Why does right-clicking create an orange dot in the center of the circle?
body: <p>Why does <a href="http://kivy.org/docs/guide/firstwidget.html" rel="noreferrer">the first widget example</a> in kivy lead to an orange circle in the middle of the yellow one when you right click on the canvas and a pure yellow one when you left click?</p>
  
  <pre><code>from kivy.app import App
  from kivy.uix.widget import Widget
  from kivy.graphics import Color, Ellipse
  
  class MyPaintWidget(Widget):
      def on_touch_down(self, touch):
          with self.canvas:
              Color(1, 1, 0)
              d = 30.
              Ellipse(pos=(touch.x - d/2, touch.y - d/2), size=(d, d))
  
  
  class MyPaintApp(App):
      def build(self):
          return MyPaintWidget()
  
  
  if __name__ == '__main__':
      MyPaintApp().run()
  </code></pre>