function onBeforeUnloadAction(){
   return "If you just want to close the light box, please use the \'Close ' button in lightbox instead. \n\nHowever, if you want to leave MoonSha\'s website, please select (OK) to close";
 }
 window.onbeforeunload = function(){
   if((window.event.clientX<0) || 
      (window.event.clientY<0)){ 
     return onBeforeUnloadAction();
   }
 }