Petzold.SelectColor.ColorCell.OnRender C# (CSharp) Method

        protected override void OnRender(DrawingContext dc)
        {
            Rect rect = new Rect(new Point(0,0), RenderSize);
            rect.Inflate(-1, -1);
            Pen pen = new Pen(SystemColors.HighlightBrush, 1);

            if (IsHighlighted)
                dc.DrawRectangle(SystemColors.ControlDarkBrush, pen, rect);
            else if (IsSelected)
                dc.DrawRectangle(SystemColors.ControlLightBrush, pen, rect);
            else
                dc.DrawRectangle(Brushes.Transparent, null, rect);
        }