Set LineJoin for Pen

   
 

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

public class Form1 : Form {

    protected override void OnPaint(PaintEventArgs e) {
    Graphics g = e.Graphics;
    g.SmoothingMode = SmoothingMode.AntiAlias;
    g.FillRectangle(Brushes.White, this.ClientRectangle);

    Pen p = new Pen(Color.Black, 10);
    p.LineJoin = LineJoin.Bevel;
    e.Graphics.DrawRectangle(p, 20, 20, 60, 60);
    p.Dispose();
    }
    public static void Main() {
        Application.Run(new Form1());
    }
}