function clickHandler (evt) {
  if (document.layers)
    return false;
  else if (evt.stopPropagation) {
    evt.stopPropagation();
    evt.preventDefault();
  }
  else if (window.event)
    return false;
}
function initClickPrevention () {
  if (document.layers) {
    window.captureEvents(Event.CLICK);
    window.onclick = clickHandler;
  }
  else if (document.all && !document.getElementById)
    document.onclick = clickHandler;
  else if (document.all)
    document.attachEvent('onclick', clickHandler);
  else if (document.addEventListener)
    document.addEventListener('click', clickHandler, true);
}
function stopClickPrevention () {
  if (document.layers) {
    window.releaseEvents(Event.CLICK);
    window.onclick = null;
  }
  else if (document.all && !document.getElementById)
    document.onclick = null;
  else if (document.all)
    document.detachEvent('onclick', clickHandler);
  else if (document.addEventListener)
    document.removeEventListener('click', clickHandler, true);
}
initClickPrevention();