How to draw rounded corners in WinForm

using System;
using ;
using ;
using ;
using ;
using ;
using ;
using ;
using ;
using .Drawing2D;
namespace AppStartSample
{
 public partial class Form3 : Form
 {
  public Form3()
  {
   InitializeComponent();
  }
  private void button1_Click(object sender, EventArgs e)
  {
  }
  private void button2_Click(object sender, EventArgs e)
  {
  }
  public void SetWindowRegion()
  {
   . FormPath;
   FormPath = new .();
   Rectangle rect = new Rectangle(0, 22, ,  - 22);//
   FormPath = GetRoundedRectPath(rect, 30);
    = new Region(FormPath);
  }
  private GraphicsPath GetRoundedRectPath(Rectangle rect, int radius)
  {
   int diameter = radius;
   Rectangle arcRect = new Rectangle(, new Size(diameter, diameter));
   GraphicsPath path = new GraphicsPath();
   // upper left corner   (arcRect, 180, 90);
   // upper right corner    =  - diameter;
   (arcRect, 270, 90);
   // Lower right corner    =  - 0;
   (arcRect, 0, 90);
   // Lower left corner    = ;
   (arcRect, 90, 90);
   ();
   return path;
  }
  protected override void OnResize( e)
  {
    = null;
   SetWindowRegion();
  }
 }
}