GUI Windows Form C#

using System;
using System.Drawing;
using System.Windows.Forms;
   
class FormSize: Form
{
     public static void Main()
     {
          Application.Run(new FormSize());
     }
     public FormSize()
     {
          BackColor = Color.White;
     }
     protected override void OnResize(EventArgs ea)
     {
          Invalidate();
     }
     protected override void OnPaint(PaintEventArgs pea)
     {
          Graphics graphics = pea.Graphics;
          string   str  = "Location: "        + Location        + "\n"   +
                          "ClientRectangle: " + ClientRectangle;
   
          graphics.DrawString(str, Font, Brushes.Black, 0, 0);
    }
}