var mymessage = " All content on this page is the property of Villa Rental Ibiza";

function rtclickcheck(keyp){

  if (navigator.appName == "Netscape" && keyp.which == 3) {
    alert(mymessage);
    return false;
  }


  if (navigator.appVersion.indexOf("MSIE") != -1 && event.button == 2) { 
    alert(mymessage);
    return false;
  }
}

document.onmousedown = rtclickcheck