On MacOS using VSCode. I was trying to create a modern splash screen using Kivy in Python. Heres my code:

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.graphics import Color, RoundedRectangle
from kivy.core.window import Window

class RoundedWindow(FloatLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        with self.canvas.before:
            Color(0.6, 0.4, 0.8, 1)
            self.rect = RoundedRectangle(size = self.size, pos = self.pos, radius = [36])
        self.bind(size = self.update_rect, pos=self.update_rect)

    def update_rect(self, instance, value):
        self.rect.pos = self.pos
        self.rect.size = self.size

class RoundedWindowApp(App):
    def build(self):
        Window.borderless = True  
        Window.size = (360, 360) 
        return RoundedWindow()

if __name__ == '__main__':
    RoundedWindowApp().run()

When ran, the Kivy window’s titlebar was removed, but the attempt at making the new window have corner radius failed. It shows this:

web image

How do I remove the black corner?