Orbit Top Most ?

[charqus]

Hello guys. I made an orbit ( circle ) and a ball. I built the code , like the ball to move on the orbit. But i have a problem with the orbit , because it flash. Is there any option like the orbit to don't flash ?
Here's the source code:

private void Form1_Paint(object sender, PaintEventArgs e)
        {
            SolidBrush redBrush = new SolidBrush(Color.RoyalBlue);
            SolidBrush black = new SolidBrush(Color.Black);

            float x0;
            float y0;
            int k;
            double pi = Math.PI, pas = pi / 18;
            int n = 2;
            double u = (2 * pi) / n;
            n = 1;
            u = (2 * pi) / n;
            
            while (true)
            {            
          e.Graphics.DrawEllipse(Pens.AliceBlue, 50, 50, 200, 200);
                x0 = 144 + 100 * (float)Math.Cos(u);
                y0 = 144 + 100 * (float)Math.Sin(u);
                e.Graphics.FillEllipse(redBrush, x0, y0, 12, 12);
                Thread.Sleep(50);

//===============================================
               
                e.Graphics.DrawEllipse(Pens.Black, 50, 50, 200, 200);
                x0 = 144 + 100 * (float)Math.Cos(u);
                y0 = 144 + 100 * (float)Math.Sin(u);
                e.Graphics.FillEllipse(black, x0, y0, 12, 12);
                Thread.Sleep(2);

                u = u + pas;
                if (u >= 2*pi) u = 0;
            }
}

Here is the application:

http://www.2shared.com/file/12790047/e0d291ac/Elipse_C_Sharp_.html