Rounded Corners in a data grid (help needed asap)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;


namespace RndCorner
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Region = System.Drawing.Region.FromHrgn(CreateRoundRectRgn( 0, 0,Width-10, Height-10, 20, 20));

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
        [DllImport("Gdi32.dll", EntryPoint = "CreateRoundRectRgn")]

        private static extern IntPtr CreateRoundRectRgn(
            int nLeftRect, // x-coordinate of upper-left corner
            int nTopRect, // y-coordinate of upper-left corner
            int nRightRect, // x-coordinate of lower-right corner
            int nBottomRect, // y-coordinate of lower-right corner
            int nWidthEllipse, // height of ellipse
            int nHeightEllipse // width of ellipse
            );
    }
}

namespace RndCornerGrid
{
    public partial class MyCustomDataGridView : DataGridView
    {
        public MyCustomDataGridView()
            : base()
        {
            Region = System.Drawing.Region.FromHrgn(CreateRoundRectRgn( 0, 0,Width-10, Height-10, 20, 20));
        }

        [DllImport("Gdi32.dll", EntryPoint = "CreateRoundRectRgn")]
        private static extern IntPtr CreateRoundRectRgn(
            int nLeftRect, // x-coordinate of upper-left corner
            int nTopRect, // y-coordinate of upper-left corner
            int nRightRect, // x-coordinate of lower-right corner
            int nBottomRect, // y-coordinate of lower-right corner
            int nWidthEllipse, // height of ellipse
            int nHeightEllipse // width of ellipse
            );
    }
}