Simple drag&drop from label text to textbox

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

namespace DragDrop
{
    public partial class Form1 : Form
    {
        private Label label1;
        private Label label2;
        private Label label3;
        private TextBox dropTxb;

        public Form1()
        {          
            // Init the form.
            InitializeComponent();

            // Install our controls.
            label1 = new Label();
            label2 = new Label();
            label3 = new Label();
            dropTxb = new TextBox();

            // Place 3 labels
            label1.Location = new Point(100, 30);
            label1.Text = "One";
            label2.Location = new Point(100, 60);
            label2.Text = "Two";
            label3.Location = new Point(100, 90);
            label3.Text = "Three";

            // and a textbox on the form.
            dropTxb.Location = new Point(100, 180);
            this.dropTxb.Size = new Size(100, 20);
            dropTxb.AllowDrop = true; //essential

            // Handle mousedowns of all the labels with the same method.
            label1.MouseDown += new MouseEventHandler(labelMouseDown);
            label2.MouseDown += new MouseEventHandler(labelMouseDown);
            label3.MouseDown += new MouseEventHandler(labelMouseDown);

            // Install two drageventhandlers for our textbox.
            dropTxb.DragEnter += new DragEventHandler(this.dropTxb_DragEnter);
            dropTxb.DragDrop += new DragEventHandler(dropTxb_DragDrop);            
           
            // Add our controls to the controls collection of the form.
            this.Controls.Add(label1);
            this.Controls.Add(label2);
            this.Controls.Add(label3);
            this.Controls.Add(dropTxb);
        }

        void labelMouseDown(object sender, MouseEventArgs e)
        {
            // We know sender is a label find out which.
            Label Lbl = sender as Label;
            // Get the label text and start the whole thing up.
            Lbl.DoDragDrop(Lbl.Text, DragDropEffects.Copy);
        }

        private void dropTxb_DragEnter(object sender, DragEventArgs e)
        {
            // Check if the data we are dragging is text.
            // Data gets the IDataObject that contains the data associated with the dragevent.
            if (e.Data.GetDataPresent("Text"))
            {
                e.Effect = DragDropEffects.Copy;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }

        private void dropTxb_DragDrop(object sender, DragEventArgs e)
        {
            // Get the textdata object and cast to string
            // Data gets the IDataObject that contains the data associated with the dragevent.
            dropTxb.Text = e.Data.GetData(DataFormats.Text) as String;
            // Show we were here
            // Had to do this for Momerath and Mitja LOL
            StringBuilder sb = new StringBuilder();
            sb.Append("The text ");
            sb.Append("\"");
            sb.Append(dropTxb.Text);
            sb.Append("\"");
            sb.Append(" was dropped in the textbox.");
            MessageBox.Show(sb.ToString());
        } 
    }
}