rem: return event.pageX || (event.clientX + 
add: return event.pageX || (event.clientX + 
context:   pointerX: function(event) {    return event.pageX || (event.clientX +       (document.documentElement.scrollLeft || document.body.scrollLeft));  },
meta: 3974	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/3974/af9adbf17404d887f31369756326b0109da7ae2b/prototype.js/buggy/root/static/js/prototype.js