rem: return event.pageY || (event.clientY + 
add: return event.pageY || (event.clientY + 
context:   pointerY: function(event) {    return event.pageY || (event.clientY +      (document.documentElement.scrollTop || document.body.scrollTop));  },
meta: 1782	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/1782/3f0bcc29b1d13b6ec87c6b75980c7f271e175e80/prototype.js/buggy/webapp/sandbox/scripts/prototype.js