public static byte? ShowDialog(Window owner, byte maxLevel)
 {
     EVTrainingWindow window = new EVTrainingWindow(maxLevel);
     window.Owner = owner;
     var result = window.ShowDialog();
     if (result.HasValue && result.Value) {
         return window.level;
     }
     return null;
 }
        public static byte?ShowDialog(Window owner, byte maxLevel)
        {
            EVTrainingWindow window = new EVTrainingWindow(maxLevel);

            window.Owner = owner;
            var result = window.ShowDialog();

            if (result.HasValue && result.Value)
            {
                return(window.level);
            }
            return(null);
        }