C# - Lendo um arquivo de texto em textBox

Lendo um arquivo e Exibindo num textBox,
com quebra de linhas.

//Lendo um arquivo e Exibindo num textBox

//Com quebra de linhas

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using System.IO;

namespace keypress {

    public partial class Form1 : Form {

        public System.Windows.Forms.TextBox textBox;

        String str = "";

        /*============================================================*/

        public void Arquivo_Txt ( ) {

            textBox = new System.Windows.Forms.TextBox ( );

            int counter = 0;

            System.IO.StreamReader file =

                new System.IO.StreamReader ( "H:\\eclipse luna_two\\"

                  + "PROJETO\\PROJETO\\src\\Poesias famosas.txt" );

            try {

                while ( ( str = file.ReadLine ( ) ) != null ) {

                    str += "\n";

                    counter++;

                    textBox.Text += counter + "   ";

                    textBox.Text += str + "\r\n";

                }

                file.Close ( );

            } catch ( Exception e ) {

                MessageBox.Show ( "Não é possivel ler o arquivo" );

                MessageBox.Show ( e.Message );

            }

        }

        /*============================================================*/

        public void text_Box ( ) {

            textBox.ForeColor = Color.Black;

            textBox.Multiline = true;

            textBox.ScrollBars = ScrollBars.Vertical;

            textBox.Size = new System.Drawing.Size ( 565, 210 );

            textBox.Location = new Point ( 10, 40 );

            textBox.Font = new Font ( "Times New Roman", 12F,

            System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, 0 );

        }

        /*============================================================*/

        protected override void OnPaint ( PaintEventArgs e ) {

            this.Size = new System.Drawing.Size ( 600, 300 );

            this.Text = "Lendo um arquivo de texto em textBox";

            this.BackColor = Color.LightBlue;

            Graphics dc = e.Graphics;

            Pen BluePen = new Pen ( Color.Coral, 10 );

            dc.DrawRectangle ( BluePen, 5, 5, 575, 250 );

            Font myFont = new System.Drawing.Font ( "Helvetica", 14,

                FontStyle.Italic );

             Brush myBrush = new SolidBrush ( System.Drawing.Color.Black );

             dc.DrawString ( "Lendo um arquivo de texto em textBox",

            myFont, myBrush, 130, 10 );

        }

        /*============================================================*/

        public Form1 ( ) {

            Arquivo_Txt ( );

            text_Box ( );

            this.Controls.Add ( this.textBox );

        }

        /*============================================================*/

    }

    static class Program {

        /// <summary>

        /// The main entry point for the application.

        /// </summary>

        [STAThread]

        static void Main ( ) {

            Application.EnableVisualStyles ( );

            Application.SetCompatibleTextRenderingDefault ( false );

            Application.Run ( new Form1 ( ) );

        }

    }

}