/// <summary>
        /// Default constructor.
        /// </summary>
        public SurfaceWindow1()
        {
            InitializeComponent();

            // Add handlers for window availability events
            AddWindowAvailabilityHandlers();

            TTTboard _new = new TTTboard(board_view);
            board_view.Items.Add(_new.getView());
        }
        private void change(object sender, RoutedEventArgs e)
        {
            SurfaceButton cur_ele = (SurfaceButton)sender;
            string content = cur_ele.Content.ToString();

            if (content.Equals("") && (!win)) // if the cell is empty, and havn't found a winner yet.
            {
                int col = Grid.GetColumn(cur_ele);
                int row = Grid.GetRow(cur_ele);
                count++;

                cur_ele.Content = current;

                current = current.Equals("X") ? "O" : "X";

                perGrid[row, col] = current; // set the cell content as marked sign

                win = winner_Checker(current); // check winner

                if (win || count == 9)
                {
                    TTTboard _new = new TTTboard(main_view);
                    main_view.Items.Add(_new.getView());
                }

            }
            else if (content.Equals("") && (win)) // if the cell is empty, and found a winner.
            {
                cur_ele.IsEnabled = false;// disable the cell from marking new one.

                return;
            }
        }