C#

protected override  CreateParams CreateParams 
{ 
  get 
  { 
    CreateParams cp=base.CreateParams; 
    cp.ExStyle|=0x00000020; //WS_EX_TRANSPARENT 
    return cp; 
  } 
} 
protected override  void OnPaintBackground(PaintEventArgs pevent) 
{ 
  //do not allow the background to be painted  
}  

using System; 
using System.Collections.Generic; 
using System.Text; 
using System.Windows.Forms; 
using System.Drawing; 
namespace WindowsApplication16 
{ 
    public class HrisTranspControl : Control 
    { 
        private Pen _drawingPen; 
        public HrisTranspControl() 
        { 
            Random rnd = new Random(); 
            this._drawingPen = new System.Drawing.Pen(new System.Drawing.SolidBrush(System.Drawing.Color.FromArgb(rnd.Next(0,255),rnd.Next(0,255), rnd.Next(0,255))),5); 
        } 
        protected override CreateParams CreateParams 
        { 
            get 
            { 
                CreateParams cp = base.CreateParams; 
                cp.ExStyle |= 0x00000020; 
                return cp; 
            } 
        } 
        protected override void OnPaintBackground(PaintEventArgs pevent) 
        { 
            // Do nothing 
        } 
        protected override void OnPaint(PaintEventArgs e) 
        { 
            base.OnPaint(e); 
            e.Graphics.DrawLine(_drawingPen, new System.Drawing.Point(0, 0), new System.Drawing.Point(this.Width, this.Height)); 
        } 
    } 
}