public class GridRightSideHelper : GridSplitter
    {
        private static readonly Dictionary<DependencyObject, GridLength> ValuesList = new Dictionary<DependencyObject, GridLength>();

        public static GridSplitter GetRightSideWatch(DependencyObject obj)
        {
            return (GridSplitter)obj.GetValue(RightSideWatchProperty);
        }

        public static void SetRightSideWatch(DependencyObject obj, GridSplitter value)
        {
            obj.SetValue(RightSideWatchProperty, value);
        }

        public static readonly DependencyProperty RightSideWatchProperty = DependencyProperty.RegisterAttached(
            "RightSideWatch", typeof(GridSplitter), typeof(DependencyObject), new UIPropertyMetadata(null, OnRightSideWatchChanged));

        private static void OnRightSideWatchChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            if (obj == null) return;

            if (obj is Grid)
            {
                var grid = obj as Grid;
                var gs = e.NewValue as GridSplitter;
                if (gs != null)
                {
                    gs.IsVisibleChanged += (sender, args) => UpdateGrid(grid, (bool)args.NewValue);
                }
            }
        }


        private static void UpdateGrid(Grid grid, bool newValue)
        {
            var prev = grid.ColumnDefinitions.ElementAt(0);
            var curr = grid.ColumnDefinitions.ElementAt(1);
            var next = grid.ColumnDefinitions.ElementAt(2);

            if (newValue)
            {
                ValuesList[prev] = prev.Width;
                ValuesList[curr] = curr.Width;
                ValuesList[next] = next.Width;
            }
            else
            {
                if (ValuesList.Count != 0)
                {
                    grid.ColumnDefinitions.ElementAt(0).Width = ValuesList[prev];
                    grid.ColumnDefinitions.ElementAt(1).Width = ValuesList[curr];
                    grid.ColumnDefinitions.ElementAt(2).Width = ValuesList[next];
                }
            }
        }
    }