System information

• OpenCV => 3.3.0
• Operating System / Platform => macOS 10.12.6 (Sierra)
• Compiler => Xcode 9.0.1
• QT => 5.9.2

Detailed description

waitKey() fail to capturing arrow keys.

Steps to reproduce

Build and run the following code:

#include <cstdio>
#include <cstdlib>

#include <opencv2/opencv.hpp>

 int main (int argc, char * const argv[]) {

      cv::namedWindow("window");

      cv::Mat image(320, 240, CV_8UC3, cv::Scalar(0,0,0));

      cv::imshow("window", image);

      while(1){

           int key = cv::waitKey(0);
    
           printf("DEGUG pressed key %d (%c)\n", key, key);

    }

}

Press some random keys with the window focused and not. At a certain point the arrow keys are no more capturing. It's like a random bug so sometimes the above procedure has to be executed several times.