var popup = "Copyright ©1999 - 2008 Boiana-MG ";
function noway (go) {
  if (document.all) {
    if (event.button == 2) {
      alert(popup);
      return false;
    }
  }
  if (document.layers) {
    if (go.which == 3) {
      alert(popup);
      return false;
    }
  }
}

if (document.layers) {
  document.captureEvents(Event.MOUSEDOWN);
}

document.onmousedown = noway;