Player plays half-transparent video on top of other windows

transparent_player.py

"""
sudo apt install libgirepository1.0-dev gcc libcairo2-dev pkg-config python3-dev gir1.2-gtk-4.0
pip install pycairo PyGObject opencv-python
"""

import cv2
import gi
import numpy as np

gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, Gdk, GdkPixbuf, GLib


class VideoWindow(Gtk.Window):
    def __init__(self):
        super(VideoWindow, self).__init__()
        self.set_decorated(False)
        self.set_position(Gtk.WindowPosition.NONE)
        self.move(0, 0)
        screen = self.get_screen()
        visual = screen.get_rgba_visual()
        if visual and screen.is_composited():
            self.set_visual(visual)
        self.set_app_paintable(True)
        self.connect("draw", self.area_draw)
        GLib.timeout_add(33, self.update_frame)

        self.dst = None
        self.open_video()

        visual = screen.get_rgba_visual()
        print(f'Visual: {visual}, Composited: {screen.is_composited()}')
        if visual and screen.is_composited():
            self.set_visual(visual)
        else:
            print("Transparency not supported")

    def open_video(self):
        self.color_cap = cv2.VideoCapture('color.mp4')
        self.alpha_cap = cv2.VideoCapture('alpha.mp4')

    def area_draw(self, widget, cr):
        if self.dst is not None:
            height, width, _ = self.dst.shape
            self.set_size_request(width, height)
            dst_gtk = GdkPixbuf.Pixbuf.new_from_data(
                self.dst.tobytes(), GdkPixbuf.Colorspace.RGB, True, 8, width, height, width * 4
            )
            Gdk.cairo_set_source_pixbuf(cr, dst_gtk, 0, 0)
            cr.paint()

    def update_frame(self):
        ret_color, color_frame = self.color_cap.read()
        ret_alpha, alpha_frame = self.alpha_cap.read()

        if not ret_color or not ret_alpha:
            self.open_video()
            ret_color, color_frame = self.color_cap.read()
            ret_alpha, alpha_frame = self.alpha_cap.read()
            assert ret_color and ret_alpha

        # Convert the alpha frame to single channel
        alpha = cv2.cvtColor(alpha_frame, cv2.COLOR_BGR2GRAY)

        # Merge the color and alpha channels
        b, g, r = cv2.split(color_frame)
        rgba = [r, g, b, alpha]
        self.dst = cv2.merge(rgba, 4)

        self.queue_draw()
        return True

if __name__ == "__main__":
    win = VideoWindow()
    win.show_all()
    Gtk.main()