Teste Revisão DragandDrop

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;
namespace _teste_2
{
public partial class Form1 : Form
 {
 int[] array = new int[9];
 int wincount = 0;
 public Form1()
 {
 InitializeComponent();
 }
 private void button1_Click(object sender, EventArgs e)
 {
 upButtons();
 randoms();
 downButtons();
 button1.Enabled = false;
 }
 private void randoms()
 {
 Random rnd = new Random();
 for (int i = 1; i <= 9; i++)
 {
 int x = rnd.Next(0, 9);
while (array[x] > 0)
 x = rnd.Next(0, 9);
 array[x] = i;
 }
 }
 private void upButtons()
 {
 for (int i = 1; i <= 9; i++)
 {
 Button upBtn = new Button();
 upBtn.Name = "upBtn" + i;
 upBtn.Text = "" + i;
 upBtn.Size = new System.Drawing.Size(30, 30);
 upBtn.Location = new System.Drawing.Point(120 + 40 * i, 70);
 upBtn.MouseDown += new MouseEventHandler(this.upBtn_MouseDown);
 upBtn.DragOver += new DragEventHandler(this.Btn_DragOver);
 upBtn.DragDrop += new DragEventHandler(this.Btn_DragDrop);
 upBtn.AllowDrop = true;
 Controls.Add(upBtn);
 }
 }
 private void downButtons()
 {
 int count = 1;
 for (int i = 1; i <= 3; i++)
 {
 for (int h = 1; h <= 3; h++)
 {
 Button downBtn = new Button();
 downBtn.Name = "downBtn" + array[count - 1];
 downBtn.Size = new System.Drawing.Size(50, 50);
 downBtn.Location = new System.Drawing.Point(220 + 60 * i, 100 +
60 * h);
 downBtn.BackColor = Color.Orange;
 downBtn.DragOver += new DragEventHandler(this.Btn_DragOver);
 downBtn.DragDrop += new DragEventHandler(this.Btn_DragDrop);
 downBtn.AllowDrop = true;
 Controls.Add(downBtn);
 count++;
 }
 }
 }
 private void upBtn_MouseDown(object sender, MouseEventArgs e)
 {
 DoDragDrop(sender, DragDropEffects.Move);
 }
 private void Btn_DragOver(object sender, DragEventArgs e)
 {
 if (e.Data.GetDataPresent(typeof(Button)))
 e.Effect = DragDropEffects.Move;
 else
 e.Effect = DragDropEffects.None;
 }
 private void Btn_DragDrop(object sender, DragEventArgs e)
 {
 var upBtn = e.Data.GetData(typeof(Button)) as Button;
 var downBtn = sender as Button;
 if (upBtn.Text[0] == downBtn.Name[7])
 {
 downBtn.Text = upBtn.Text;
 wincount++;
 }
 if (wincount == 9)
 {
 label1.Visible = true;
 button2.Focus();
 }
 }
 private void button2_Click(object sender, EventArgs e)
 {
 Environment.Exit(0);
 }
 }
}