Getting a grid of buttons without the spacing in between.

What do I need to do to avoid the default spacing between two buttons? I have tried setting padding to 0, BorderWidth etc. I am using Grid like this:

  in ctor: 

        InitializeComponent();
        var grid = new Grid
        {

            RowSpacing = 0,
            ColumnSpacing = 1,
            HorizontalOptions = LayoutOptions.CenterAndExpand,
            Padding = 0,
            RowDefinitions =
            {
                new RowDefinition { Height = new GridLength(100, GridUnitType.Auto) },
                   .... 9 more

            },
            ColumnDefinitions =
            {
                new ColumnDefinition{ Width = new GridLength(100, GridUnitType.Auto) },
                .... 9 more                }

        };


        const int numCols = 10;
        const int numRows = 10;
        for (int i = 0; i < numCols; i++)
            for (int k = 0; k < numRows; k++)
            {

                var gridButton = new Button
                {
                    Text = (i).ToString() + "," + (k).ToString(),

                    BorderWidth = 0,
                    BorderRadius = 0,
                    HorizontalOptions = LayoutOptions.FillAndExpand,
                    // Bounds = new Rectangle(50*i,50*k, 50, 50)

                };
                gridButton.Clicked += delegate
                {

                    gridButton.Text = string.Format("{0}", count++);
                };
                grid.Children.Add( gridButton, i, k); // Left, Third element
            }

        this.Content = grid;
    }