Tråd problemer

Hej Alle sammen

Jeg har et problem med trådningen af et program.

Når jeg klikker på det røde X på min form og vinduet forsvinder, så fortsætter alle baggrunds trådene.

Hvordan fanger jeg X's event, og afslutter alle baggrunds tråde ?

Mvh.
Jens

EKS på problemet:

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Threading;

namespace trådProblem
{
    /// <summary>
    /// Summary description for Form1.
    /// </summary>
    public class Form1 : System.Windows.Forms.Form
    {
        private System.Windows.Forms.Button button1;
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components = null;

        public Form1()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();

            //
            // TODO: Add any constructor code after InitializeComponent call
            //
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.button1 = new System.Windows.Forms.Button();
            this.SuspendLayout();
            //
            // button1
            //
            this.button1.Location = new System.Drawing.Point(16, 32);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(192, 40);
            this.button1.TabIndex = 0;
            this.button1.Text = "start tråd";
            this.button1.Click += new System.EventHandler(this.button1_Click);
            //
            // Form1
            //
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(216, 110);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                          this.button1});
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);

        }
        #endregion

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.Run(new Form1());
        }

        private void button1_Click(object sender, System.EventArgs e)
        {
                    //Opretter loop objekt
                  loop test = new loop();
           
            //Opretter og starter tråd.
            Thread T = new Thread(new ThreadStart(test.startLoop));
            T.Start();
        }
    }
    class loop
    {
        public void startLoop()
        {
            //Sætter prioiten til lav.
        System.Threading.Thread.CurrentThread.Priority = System.Threading.ThreadPriority.Lowest;

            double i = 1;
            while(true)
            {
                i=0;
            }
        }
    }
}