Mesajlı sağ tık engeli

<script language="Javascript1.2"> 

 
var mymessage = "YASSAK KARDEŞİM YASSAK 
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
//-->
</script>