function right(e) {
  var msg = "Sorry, you don't have permission to right-click.";
  if (navigator.appName == 'Netscape' && e.which == 3) {
    alert(msg);
    return false;
  }
  if (navigator.appName == 'Microsoft Internet Explorer' && event.button==2) {
    alert(msg);
    return false;
  }
  else return true;
}

function trap() {
  if(document.images)
    {
    for(i=0;i<document.images.length;i++)
      {
      document.images[i].onmousedown = right;
      document.images[i].onmouseup = right;
      }
    }
  }