public void Shuffle()
        {
            var points = new Point[]{
                new Point(0, 0),
                new Point(1, 0),
                new Point(2, 0),
                new Point(0, 1),
                new Point(1, 1),
                new Point(2, 1),
                new Point(0, 2),
                new Point(1, 2),
                new Point(2, 2)
            };

            points.Shuffle ();

            for ( int i = 0; i < 9; i++ ) {
                Items[ i ].Location = points[ i ];
            }

            CauseUpdate ();
        }