if (document.all) {
  document.onmousedown = mouse_down;
}
else if (document.layers) 
{
  window.onmousedown = mouse_down;
  window.captureEvents(Event.MOUSEDOWN);
}


function mouse_down(e)
{
  if (document.all) 
  {
    if (event.button == 2)
    {
      window.close();
    }
  }
  else if (document.layers) 
  {
    if (e.which == 3) 
    {
      window.close();
    }
  }
}