The source code

    /*!
     * Ext JS Library 3.2.1
     * Copyright(c) 2006-2010 Ext JS, Inc.
     * licensing@extjs.com
     * http://www.extjs.com/license
     */
    /**
     * @class Ext.Element
     */
    Ext.Element.addMethods(function(){
        // local style camelizing for speed
        var propCache = {},
            camelRe = /(-[a-z])/gi,
            classReCache = {},
            view = document.defaultView,
            propFloat = Ext.isIE ? 'styleFloat' : 'cssFloat',
            opacityRe = /alpha\(opacity=(.*)\)/i,
            trimRe = /^\s+|\s+$/g,
            spacesRe = /\s+/,
            wordsRe = /\w/g,
            EL = Ext.Element,
            PADDING = "padding",
            MARGIN = "margin",
            BORDER = "border",
            LEFT = "-left",
            RIGHT = "-right",
            TOP = "-top",
            BOTTOM = "-bottom",
            WIDTH = "-width",
            MATH = Math,
            HIDDEN = 'hidden',
            ISCLIPPED = 'isClipped',
            OVERFLOW = 'overflow',
            OVERFLOWX = 'overflow-x',
            OVERFLOWY = 'overflow-y',
            ORIGINALCLIP = 'originalClip',
            // special markup used throughout Ext when box wrapping elements
            borders = {l: BORDER + LEFT + WIDTH, r: BORDER + RIGHT + WIDTH, t: BORDER + TOP + WIDTH, b: BORDER + BOTTOM + WIDTH},
            paddings = {l: PADDING + LEFT, r: PADDING + RIGHT, t: PADDING + TOP, b: PADDING + BOTTOM},
            margins = {l: MARGIN + LEFT, r: MARGIN + RIGHT, t: MARGIN + TOP, b: MARGIN + BOTTOM},
            data = Ext.Element.data;

        // private
        function camelFn(m, a) {
            return a.charAt(1).toUpperCase();
        }

        function chkCache(prop) {
            return propCache[prop] || (propCache[prop] = prop == 'float' ? propFloat : prop.replace(camelRe, camelFn));
        }

        return {
            // private  ==> used by Fx
            adjustWidth : function(width) {
                var me = this;
                var isNum = (typeof width == "number");
                if(isNum && me.autoBoxAdjust && !me.isBorderBox()){
                   width -= (me.getBorderWidth("lr") + me.getPadding("lr"));
                }
                return (isNum && width < 0) ? 0 : width;
            },

            // private   ==> used by Fx
            adjustHeight : function(height) {
                var me = this;
                var isNum = (typeof height == "number");
                if(isNum && me.autoBoxAdjust && !me.isBorderBox()){
                   height -= (me.getBorderWidth("tb") + me.getPadding("tb"));
                }
                return (isNum && height < 0) ? 0 : height;
            },

            /**
             * Adds one or more CSS classes to the element. Duplicate classes are automatically filtered out.
             * @param {String/Array} className The CSS class to add, or an array of classes
             * @return {Ext.Element} this
             */
            addClass : function(className){
                var me = this,
                    i,
                    len,
                    v,
                    cls = [];
                // Separate case is for speed
                if (!Ext.isArray(className)) {
                    if (typeof className == 'string' && !this.hasClass(className)) {
                        me.dom.className += " " + className;
                    }
                }
                else {
                    for (i = 0, len = className.length; i < len; i++) {
                        v = className[i];
                        if (typeof v == 'string' && (' ' + me.dom.className + ' ').indexOf(' ' + v + ' ') == -1) {
                            cls.push(v);
                        }
                    }
                    if (cls.length) {
                        me.dom.className += " " + cls.join(" ");
                    }
                }
                return me;
            },

            /**
             * Removes one or more CSS classes from the element.
             * @param {String/Array} className The CSS class to remove, or an array of classes
             * @return {Ext.Element} this
             */
            removeClass : function(className){
                var me = this,
                    i,
                    idx,
                    len,
                    cls,
                    elClasses;
                if (!Ext.isArray(className)){
                    className = [className];
                }
                if (me.dom && me.dom.className) {
                    elClasses = me.dom.className.replace(trimRe, '').split(spacesRe);
                    for (i = 0, len = className.length; i < len; i++) {
                        cls = className[i];
                        if (typeof cls == 'string') {
                            cls = cls.replace(trimRe, '');
                            idx = elClasses.indexOf(cls);
                            if (idx != -1) {
                                elClasses.splice(idx, 1);
                            }
                        }
                    }
                    me.dom.className = elClasses.join(" ");
                }
                return me;
            },

            /**
             * Adds one or more CSS classes to this element and removes the same class(es) from all siblings.
             * @param {String/Array} className The CSS class to add, or an array of classes
             * @return {Ext.Element} this
             */
            radioClass : function(className){
                var cn = this.dom.parentNode.childNodes,
                    v,
                    i,
                    len;
                className = Ext.isArray(className) ? className : [className];
                for (i = 0, len = cn.length; i < len; i++) {
                    v = cn[i];
                    if (v && v.nodeType == 1) {
                        Ext.fly(v, '_internal').removeClass(className);
                    }
                };
                return this.addClass(className);
            },

            /**
             * Toggles the specified CSS class on this element (removes it if it already exists, otherwise adds it).
             * @param {String} className The CSS class to toggle
             * @return {Ext.Element} this
             */
            toggleClass : function(className){
                return this.hasClass(className) ? this.removeClass(className) : this.addClass(className);
            },

            /**
             * Checks if the specified CSS class exists on this element's DOM node.
             * @param {String} className The CSS class to check for
             * @return {Boolean} True if the class exists, else false
             */
            hasClass : function(className){
                return className && (' '+this.dom.className+' ').indexOf(' '+className+' ') != -1;
            },

            /**
             * Replaces a CSS class on the element with another.  If the old name does not exist, the new name will simply be added.
             * @param {String} oldClassName The CSS class to replace
             * @param {String} newClassName The replacement CSS class
             * @return {Ext.Element} this
             */
            replaceClass : function(oldClassName, newClassName){
                return this.removeClass(oldClassName).addClass(newClassName);
            },

            isStyle : function(style, val) {
                return this.getStyle(style) == val;
            },

            /**
             * Normalizes currentStyle and computedStyle.
             * @param {String} property The style property whose value is returned.
             * @return {String} The current value of the style property for this element.
             */
            getStyle : function(){
                return view && view.getComputedStyle ?
                    function(prop){
                        var el = this.dom,
                            v,
                            cs,
                            out,
                            display,
                            wk = Ext.isWebKit,
                            display;

                        if(el == document){
                            return null;
                        }
                        prop = chkCache(prop);
                        // Fix bug caused by this: https://bugs.webkit.org/show_bug.cgi?id=13343
                        if(wk && /marginRight/.test(prop)){
                            display = this.getStyle('display');
                            el.style.display = 'inline-block';
                        }
                        out = (v = el.style[prop]) ? v :
                               (cs = view.getComputedStyle(el, "")) ? cs[prop] : null;

                        // Webkit returns rgb values for transparent.
                        if(wk){
                            if(out == 'rgba(0, 0, 0, 0)'){
                                out = 'transparent';
                            }else if(display){
                                el.style.display = display;
                            }
                        }
                        return out;
                    } :
                    function(prop){
                        var el = this.dom,
                            m,
                            cs;

                        if(el == document) return null;
                        if (prop == 'opacity') {
                            if (el.style.filter.match) {
                                if(m = el.style.filter.match(opacityRe)){
                                    var fv = parseFloat(m[1]);
                                    if(!isNaN(fv)){
                                        return fv ? fv / 100 : 0;
                                    }
                                }
                            }
                            return 1;
                        }
                        prop = chkCache(prop);
                        return el.style[prop] || ((cs = el.currentStyle) ? cs[prop] : null);
                    };
            }(),

            /**
             * Return the CSS color for the specified CSS attribute. rgb, 3 digit (like #fff) and valid values
             * are convert to standard 6 digit hex color.
             * @param {String} attr The css attribute
             * @param {String} defaultValue The default value to use when a valid color isn't found
             * @param {String} prefix (optional) defaults to #. Use an empty string when working with
             * color anims.
             */
            getColor : function(attr, defaultValue, prefix){
                var v = this.getStyle(attr),
                    color = (typeof prefix != 'undefined') ? prefix : '#',
                    h;

                if(!v || /transparent|inherit/.test(v)){
                    return defaultValue;
                }
                if(/^r/.test(v)){
                    Ext.each(v.slice(4, v.length -1).split(','), function(s){
                        h = parseInt(s, 10);
                        color += (h < 16 ? '0' : '') + h.toString(16);
                    });
                }else{
                    v = v.replace('#', '');
                    color += v.length == 3 ? v.replace(/^(\w)(\w)(\w)$/, '$1$1$2$2$3$3') : v;
                }
                return(color.length > 5 ? color.toLowerCase() : defaultValue);
            },

            /**
             * Wrapper for setting style properties, also takes single object parameter of multiple styles.
             * @param {String/Object} property The style property to be set, or an object of multiple styles.
             * @param {String} value (optional) The value to apply to the given property, or null if an object was passed.
             * @return {Ext.Element} this
             */
            setStyle : function(prop, value){
                var tmp,
                    style,
                    camel;
                if (typeof prop != 'object') {
                    tmp = {};
                    tmp[prop] = value;
                    prop = tmp;
                }
                for (style in prop) {
                    value = prop[style];
                    style == 'opacity' ?
                        this.setOpacity(value) :
                        this.dom.style[chkCache(style)] = value;
                }
                return this;
            },

            /**
             * Set the opacity of the element
             * @param {Float} opacity The new opacity. 0 = transparent, .5 = 50% visibile, 1 = fully visible, etc
             * @param {Boolean/Object} animate (optional) a standard Element animation config object or true for
             * the default animation ({duration: .35, easing: 'easeIn'})
             * @return {Ext.Element} this
             */
             setOpacity : function(opacity, animate){
                var me = this,
                    s = me.dom.style;

                if(!animate || !me.anim){
                    if(Ext.isIE){
                        var opac = opacity < 1 ? 'alpha(opacity=' + opacity * 100 + ')' : '',
                        val = s.filter.replace(opacityRe, '').replace(trimRe, '');

                        s.zoom = 1;
                        s.filter = val + (val.length > 0 ? ' ' : '') + opac;
                    }else{
                        s.opacity = opacity;
                    }
                }else{
                    me.anim({opacity: {to: opacity}}, me.preanim(arguments, 1), null, .35, 'easeIn');
                }
                return me;
            },

            /**
             * Clears any opacity settings from this element. Required in some cases for IE.
             * @return {Ext.Element} this
             */
            clearOpacity : function(){
                var style = this.dom.style;
                if(Ext.isIE){
                    if(!Ext.isEmpty(style.filter)){
                        style.filter = style.filter.replace(opacityRe, '').replace(trimRe, '');
                    }
                }else{
                    style.opacity = style['-moz-opacity'] = style['-khtml-opacity'] = '';
                }
                return this;
            },

            /**
             * Returns the offset height of the element
             * @param {Boolean} contentHeight (optional) true to get the height minus borders and padding
             * @return {Number} The element's height
             */
            getHeight : function(contentHeight){
                var me = this,
                    dom = me.dom,
                    hidden = Ext.isIE && me.isStyle('display', 'none'),
                    h = MATH.max(dom.offsetHeight, hidden ? 0 : dom.clientHeight) || 0;

                h = !contentHeight ? h : h - me.getBorderWidth("tb") - me.getPadding("tb");
                return h < 0 ? 0 : h;
            },

            /**
             * Returns the offset width of the element
             * @param {Boolean} contentWidth (optional) true to get the width minus borders and padding
             * @return {Number} The element's width
             */
            getWidth : function(contentWidth){
                var me = this,
                    dom = me.dom,
                    hidden = Ext.isIE && me.isStyle('display', 'none'),
                    w = MATH.max(dom.offsetWidth, hidden ? 0 : dom.clientWidth) || 0;
                w = !contentWidth ? w : w - me.getBorderWidth("lr") - me.getPadding("lr");
                return w < 0 ? 0 : w;
            },

            /**
             * Set the width of this Element.
             * @param {Mixed} width The new width. This may be one of:
             * A Number specifying the new width in this Element's {@link #defaultUnit}s (by default, pixels).
             * A String used to set the CSS width style. Animation may not be used.
             *
             * @param {Boolean/Object} animate (optional) true for the default animation or a standard Element animation config object
             * @return {Ext.Element} this
             */
            setWidth : function(width, animate){
                var me = this;
                width = me.adjustWidth(width);
                !animate || !me.anim ?
                    me.dom.style.width = me.addUnits(width) :
                    me.anim({width : {to : width}}, me.preanim(arguments, 1));
                return me;
            },

            /**
             * Set the height of this Element.
             *
    // change the height to 200px and animate with default configuration
    Ext.fly('elementId').setHeight(200, true);

    // change the height to 150px and animate with a custom configuration
    Ext.fly('elId').setHeight(150, {
        duration : .5, // animation will have a duration of .5 seconds
        // will change the content to "finished"
        callback: function(){ this.{@link #update}("finished"); }
    });
             *
             * @param {Mixed} height The new height. This may be one of:
             * A Number specifying the new height in this Element's {@link #defaultUnit}s (by default, pixels.)
             * A String used to set the CSS height style. Animation may not be used.
             *
             * @param {Boolean/Object} animate (optional) true for the default animation or a standard Element animation config object
             * @return {Ext.Element} this
             */
             setHeight : function(height, animate){
                var me = this;
                height = me.adjustHeight(height);
                !animate || !me.anim ?
                    me.dom.style.height = me.addUnits(height) :
                    me.anim({height : {to : height}}, me.preanim(arguments, 1));
                return me;
            },

            /**
             * Gets the width of the border(s) for the specified side(s)
             * @param {String} side Can be t, l, r, b or any combination of those to add multiple values. For example,
             * passing 'lr' would get the border left width + the border right width.
             * @return {Number} The width of the sides passed added together
             */
            getBorderWidth : function(side){
                return this.addStyles(side, borders);
            },

            /**
             * Gets the width of the padding(s) for the specified side(s)
             * @param {String} side Can be t, l, r, b or any combination of those to add multiple values. For example,
             * passing 'lr' would get the padding left + the padding right.
             * @return {Number} The padding of the sides passed added together
             */
            getPadding : function(side){
                return this.addStyles(side, paddings);
            },

            /**
             *  Store the current overflow setting and clip overflow on the element - use {@link #unclip} to remove
             * @return {Ext.Element} this
             */
            clip : function(){
                var me = this,
                    dom = me.dom;

                if(!data(dom, ISCLIPPED)){
                    data(dom, ISCLIPPED, true);
                    data(dom, ORIGINALCLIP, {
                        o: me.getStyle(OVERFLOW),
                        x: me.getStyle(OVERFLOWX),
                        y: me.getStyle(OVERFLOWY)
                    });
                    me.setStyle(OVERFLOW, HIDDEN);
                    me.setStyle(OVERFLOWX, HIDDEN);
                    me.setStyle(OVERFLOWY, HIDDEN);
                }
                return me;
            },

            /**
             *  Return clipping (overflow) to original clipping before {@link #clip} was called
             * @return {Ext.Element} this
             */
            unclip : function(){
                var me = this,
                    dom = me.dom;

                if(data(dom, ISCLIPPED)){
                    data(dom, ISCLIPPED, false);
                    var o = data(dom, ORIGINALCLIP);
                    if(o.o){
                        me.setStyle(OVERFLOW, o.o);
                    }
                    if(o.x){
                        me.setStyle(OVERFLOWX, o.x);
                    }
                    if(o.y){
                        me.setStyle(OVERFLOWY, o.y);
                    }
                }
                return me;
            },

            // private
            addStyles : function(sides, styles){
                var ttlSize = 0,
                    sidesArr = sides.match(wordsRe),
                    side,
                    size,
                    i,
                    len = sidesArr.length;
                for (i = 0; i < len; i++) {
                    side = sidesArr[i];
                    size = side && parseInt(this.getStyle(styles[side]), 10);
                    if (size) {
                        ttlSize += MATH.abs(size);
                    }
                }
                return ttlSize;
            },

            margins : margins
        }
    }()
    );