public override void ReportInvalid(string keyUsed)
 {
     if (keyUsed != _apiKey)
     {
         return;
     }
     _txt.Dispatcher.Invoke(() =>
     {
         _txt.Foreground = Brushes.Red;
         LosWinAPI.FlashTaskbarIcon(new WindowInteropHelper(_window).Handle, true);
         _flashing = true;
     });
 }
 public override void ReportValid(string keyUsed)
 {
     if (keyUsed != _apiKey)
     {
         return;
     }
     _txt.Dispatcher.Invoke(() =>
     {
         _txt.Foreground = Brushes.Green;
         if (_flashing)
         {
             _flashing = false;
             LosWinAPI.FlashTaskbarStop(new WindowInteropHelper(_window).Handle);
         }
     });
 }