GUI Windows Form C#

/*
Professional Windows GUI Programming Using C#
by Jay Glynn, Csaba Torok, Richard Conway, Wahid Choudhury, 
   Zach Greenvoss, Shripad Kulkarni, Neil Whitlow
Publisher: Peer Information
ISBN: 1861007663
*/
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace UpDown_Derived
{
    /// 
    /// Summary description for UpDownDerived.
    /// 

    public class UpDownDerived : System.Windows.Forms.Form
    {
        /// 
        /// Required designer variable.
        /// 

        private System.ComponentModel.Container components = null;
        private System.Windows.Forms.Label label1;
        private MyUpDownControl mDC = null ; 
        public UpDownDerived()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();
            //
            // TODO: Add any constructor code after InitializeComponent call
            //
        }
        /// 
        /// Clean up any resources being used.
        /// 

        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null) 
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }
        #region Windows Form Designer generated code
        /// 
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// 

        private void InitializeComponent()
        {
            this.mDC = new UpDown_Derived.MyUpDownControl();
            this.label1 = new System.Windows.Forms.Label();
            this.SuspendLayout();
            // 
            // mDC
            // 
            this.mDC.Items.Add("FRANCE");
            this.mDC.Items.Add("ITALY");
            this.mDC.Items.Add("USA");
            this.mDC.Items.Add("UK");
            this.mDC.Items.Add("AUSTRALIA");
            this.mDC.Items.Add("INDIA");
            this.mDC.Items.Add("ZAMBIA");
            this.mDC.Items.Add("MALASYIA");
            this.mDC.Location = new System.Drawing.Point(40, 40);
            this.mDC.Name = "mDC";
            this.mDC.TabIndex = 0;
            // 
            // label1
            // 
            this.label1.Location = new System.Drawing.Point(16, 16);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(200, 16);
            this.label1.TabIndex = 1;
            this.label1.Text = "Derived DomainUpDown Controller";
            // 
            // UpDownDerived
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(248, 85);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                          this.label1,
                                                                          this.mDC});
            this.Name = "UpDownDerived";
            this.Text = "My Domain Controller";
            this.Load += new System.EventHandler(this.UpDownDerived_Load);
            this.ResumeLayout(false);
        }
        #endregion
        /// 
        /// The main entry point for the application.
        /// 

        [STAThread]
        static void Main() 
        {
            Application.Run(new UpDownDerived());
        }
        private void UpDownDerived_Load(object sender, System.EventArgs e)
        {
        }
    }
    /// 
    /// Summary description for MyUpDownControl.
    /// 

    public class MyUpDownControl : System.Windows.Forms.DomainUpDown  
    {
        private int currentPos  =0;
        private string DisplayText ="";
        public MyUpDownControl()
        {
            // Populate the control with items
            Items.Add("FRANCE");
            Items.Add("ITALY");
            Items.Add("USA");
            Items.Add("UK");
            Items.Add("AUSTRALIA");
            Items.Add("INDIA");
            Items.Add("ZAMBIA");
            Items.Add("MALASYIA");
        
        }
        public override void DownButton()
        {
            // Check if the Down Arrow is clicked
            currentPos ++;
            if ( currentPos >= Items.Count )
                currentPos = 0 ; 
            UpdateEditText();
        }
        public override void UpButton()
        {
            // Check if the Up Arrow is clicked
            currentPos -- ; 
            if ( currentPos < 0 ) currentPos = Items.Count-1 ; 
            UpdateEditText();
        }
        protected override void UpdateEditText()
        {
            // Update the EditBox 
            DisplayText = (string)this.Items[currentPos ];
            this.Text = DisplayText; 
        }
        public void Sort()
        {
            if ( this.Sorted ) 
                this.Sorted= false ;
            else
                this.Sorted= true ;
            if ( this.Sorted ) 
                this.Sort() ;
            
            UpdateEditText() ;
        }
    }
}