Sideshow

public class WatermarkTextBox : TextBox
    {
        private string watermarkText;
        public string WatermarkText
        {
            get { return watermarkText; }
            set { watermarkText = value; Invalidate(); }
        }

        public WatermarkTextBox()
        {
            TextChanged += ToggleWatermark;
            LostFocus += ToggleWatermark;
            Click += ToggleWatermark;
            DoubleClick += ToggleWatermark;
        }

        protected override void OnCreateControl()
        {
            base.OnCreateControl();
            ToggleWatermark(null, null);
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            using (Brush brush = new SolidBrush(Color.Silver))
            {
                e.Graphics.DrawString(WatermarkText, Font, brush, ClientRectangle, TextAlign.GetStringFormat(RightToLeft));
            }

            base.OnPaint(e);
        }

        private void ToggleWatermark(object sender, EventArgs args)
        {
            SetStyle(ControlStyles.UserPaint, Text.Length < 1);
            Invalidate();
        }
    }