1 private void button2_Click(object sender, EventArgs e)
2        {
3            this.textBox1.Text = "start";
4
5            this.backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
6            this.backgroundWorker1.RunWorkerAsync();
7        }
8
9        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
10        {
11            for (int i = 0; i < 3; i++)
12            {
13                for (int j = 0; j < 100000000; j++)
14                {
15                    j++;
16                    j--;
17                }
18                this.textBox1.Text = i.ToString();
19            }
20        }
21
22        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
23        {
24            this.textBox1.Text = "complete";
25        }