function click (e) {
  if (!e)
  e = window.event;
  if ((e.type && e.type == "contextmenu") || (e.button && e.button == 2) || (e.which && e.which == 3)) {
   return false;
  }
}


if (document.layers)
 document.captureEvents(Event.MOUSEDOWN);
document.onmousedown = click;
document.oncontextmenu = click;