import cv2
import numpy as np

frame = np.zeros((240, 320, 3), np.uint8)
window = "Test Window"

def show_window(window, frame):
    print(cv2.getWindowProperty(window, cv2.WND_PROP_TOPMOST))
    while(True):
        cv2.imshow(window, frame)
        if cv2.waitKey() > 0:
            break

cv2.namedWindow(window)

cv2.setWindowProperty(window, cv2.WND_PROP_TOPMOST, 1)
show_window(window, frame)

cv2.setWindowProperty(window, cv2.WND_PROP_TOPMOST, 0)
show_window(window, frame)