The source code

    /*!
     * Ext JS Library 3.4.0
     * Copyright(c) 2006-2011 Sencha Inc.
     * licensing@sencha.com
     * http://www.sencha.com/license
     */
    /**
     * @class Ext.Element
     */
    Ext.Element.addMethods({
        /**
         * Returns true if this element is scrollable.
         * @return {Boolean}
         */
        isScrollable : function(){
            var dom = this.dom;
            return dom.scrollHeight > dom.clientHeight || dom.scrollWidth > dom.clientWidth;
        },

        /**
         * Scrolls this element the specified scroll point. It does NOT do bounds checking so if you scroll to a weird value it will try to do it. For auto bounds checking, use scroll().
         * @param {String} side Either "left" for scrollLeft values or "top" for scrollTop values.
         * @param {Number} value The new scroll value.
         * @return {Element} this
         */
        scrollTo : function(side, value){
            this.dom["scroll" + (/top/i.test(side) ? "Top" : "Left")] = value;
            return this;
        },

        /**
         * Returns the current scroll position of the element.
         * @return {Object} An object containing the scroll position in the format {left: (scrollLeft), top: (scrollTop)}
         */
        getScroll : function(){
            var d = this.dom,
                doc = document,
                body = doc.body,
                docElement = doc.documentElement,
                l,
                t,
                ret;

            if(d == doc || d == body){
                if(Ext.isIE && Ext.isStrict){
                    l = docElement.scrollLeft;
                    t = docElement.scrollTop;
                }else{
                    l = window.pageXOffset;
                    t = window.pageYOffset;
                }
                ret = {left: l || (body ? body.scrollLeft : 0), top: t || (body ? body.scrollTop : 0)};
            }else{
                ret = {left: d.scrollLeft, top: d.scrollTop};
            }
            return ret;
        }
    });