javascript/selenium-core/lib/prototype.js
function() {
    this.deltaX =  window.pageXOffset
                || document.documentElement.scrollLeft
                || document.body.scrollLeft
                || 0;
    this.deltaY =  window.pageYOffset
                || document.documentElement.scrollTop
                || document.body.scrollTop
                || 0;
  }
function() {
    this.deltaX =  window.pageXOffset
                || document.documentElement.scrollLeft
                || document.body.scrollLeft
                || 0;
    this.deltaY =  window.pageYOffset
                || document.documentElement.scrollTop
                || document.body.scrollTop
                || 0;
  }
function ( ) { this . deltaX = window . pageXOffset || document . documentElement . scrollLeft || document . body . scrollLeft || 0 ; this . deltaY = window . pageYOffset || document . documentElement . scrollTop || document . body . scrollTop || 0 ; }
must be called before calling withinIncludingScrolloffset, every time the page is scrolled
must be called before calling withinIncludingScrolloffset every time the page is scrolled