protected override void WndProc(ref Message m)
{
 const int WM_SYSCOMMAND = 0x0112;
 const int SC_CLOSE = 0xF060;
 if (m.Msg == WM_SYSCOMMAND && (int)m.WParam == SC_CLOSE)
 {
  return;
 }
 base.WndProc(ref m);
}

protected override CreateParams CreateParams
{
 get
 {
  int CS_NOCLOSE = 0×200;
  CreateParams parameters = base.CreateParams;
  parameters.ClassStyle |= CS_NOCLOSE;
  return parameters;
 }
}