Make Corner Curve in Win C#

I have taken reference from below url for this code
http://stackoverflow.com/questions/10674228/form-with-rounded-borders-in-c


Code:

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
-----
    public partial class Form1 : Form
    {
        [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
         );

        public Form1()
        {
            InitializeComponent();
            this.FormBorderStyle = FormBorderStyle.None;
            Region = System.Drawing.Region.FromHrgn(CreateRoundRectRgn(0, 0, Width, Height, 20, 20));
        }
    }