if not all(x.is_alive() for x in self.threads) or cv2.waitKey(1) == ord("q"): # q to quit cv2.error: OpenCV(4.10.0) /io/opencv/modules/highgui/src/window.cpp:1367: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x ...