C#

private void button1_Click(object sender, EventArgs e)
{
  PrintDocument printDocument = new PrintDocument();
  printDocument.PrintPage += new PrintPageEventHandler(printDocument_PrintPage);

  PrintDialog printDialog = new PrintDialog();
  printDialog.Document = printDocument;
  DialogResult dialogResult = printDialog.ShowDialog();

  if (dialogResult == DialogResult.OK)
  {
    printDialog.Document.Print();
  }
}

private void printDocument_PrintPage(object sender, PrintPageEventArgs e)
{
  e.Graphics.DrawString("Hello World", new Font("Arial", 10), Brushes.Black, 10, 10);
}

jrahma wrote:

Actually I have posted the same question in many forums but this the first and only reply

private void InvokeShowForm(int index){
    if(InvokeRequired){
        Invoke(new ShowFormCallback(ShowForm), new object[]{index}));
    }
    else{
        ShowForm(index);
    }
}

public void ShowForm(int index){
    chatsAvailable[index].Show();
}

[DllImport("user32.dll")]
static extern bool CloseWindow(IntPtr hWnd);

[DllImport("user32.dll")]
static extern System.IntPtr FindWindow(string lpClassName, string lpWindowName);

private void button1_Click(object sender, EventArgs e)
{
  string lpClassName = "WindowClass1";
  string lpWindowName = "MyWindow1";

  IntPtr hWnd = FindWindow(lpClassName, lpWindowName);
  CloseWindow(hWnd);
}