opencv/highgui.go
func WaitKey(delay int) int {
	key := C.cvWaitKey(C.int(delay))
	return int(key)
}
func WaitKey(delay int) int {
	key := C.cvWaitKey(C.int(delay))
	return int(key)
}
/* wait for key event infinitely (delay<=0) or for "delay" milliseconds */