/// <summary>
        /// Open a SaveFileDialog to allow players to choose a location
        /// where the game will be saved.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void SaveButtonClick(object sender, RoutedEventArgs e)
        {
            PauseButtonClick(null, null);
            SaveFileDialog openFileDialog = new SaveFileDialog();

            openFileDialog.Title      = "Save the game";
            openFileDialog.FileName   = "game";
            openFileDialog.DefaultExt = ".json";
            openFileDialog.Filter     = "Text documents (.json)|*.json";

            Nullable <bool> result = openFileDialog.ShowDialog();

            if (result == true)
            {
                string filename = openFileDialog.FileName;
                game.Save(filename);
            }
        }