python - Why does right-clicking create an orange dot in the center of the circle?

Question

Why does the first widget example 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?

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()

Answer 1

To disable multi-touch emulation, add this to your source file containing your main function, before any other kivy modules are imported:

from kivy.config import Config
Config.set('input', 'mouse', 'mouse,multitouch_on_demand')