System Tray - minimizing

For my program, when it minimizes I want the dialog to close giving the illusion that it minimized to the system tray. but I don't how. it's probably a WM_SOMETHING if someone could just post a link to a page or a explanation.

thanks
cal

Code:

---

case WM_SIZE:
{
  if ( wParam & SIZE_MINIMIZED )
  {
    // window has been minimized
  }

  return 0;
}

---

Thanks Worked Great.

cal.