private void btnShowHint_Click(object sender, RoutedEventArgs e)
        {
            eWObstacles.gridRows.Visibility     = Visibility.Hidden;
            eWObstacles.gridShowAns.Visibility  = Visibility.Hidden;
            eWObstacles.gridKeyImage.Visibility = Visibility.Visible;
            eWObstacles_imgHider[currentQuestion - 1].Visibility = Visibility.Hidden; //You mustn't set the index of the comboBox here because it will enable you to open 2 hints at a time

            if (isFinished != true)                                                   //If the KEY is answered, mute this sound
            {
                ShowHintSound.Stop();
                ShowHintSound.Play();
            }
        }
 private void ShowHintSound_MediaEnded(object sender, RoutedEventArgs e)
 {
     ShowHintSound.Stop();
 }