rectangle en premier plan

public partial class Form1 : Form
{
    public Form1( )
    {
        InitializeComponent( );

        PictureBox pb = new PictureBox( );
        pb.Parent = this;
        pb.Dock = DockStyle.Fill;
        pb.Image = this.Icon.ToBitmap( );
        pb.SizeMode = PictureBoxSizeMode.StretchImage;
        pb.Paint += new PaintEventHandler( PictureBox_Paint );
    }

    private void PictureBox_Paint( object sender, PaintEventArgs e )
    {
        e.Graphics.DrawRectangle( new Pen(
            Color.Blue, 10.0f ), 10, 10, 100, 100 );
    }
}