The source code

    /**
     * @class Ext.Element
     */
    (function(){
    var D = Ext.lib.Dom,
            LEFT = "left",
            RIGHT = "right",
            TOP = "top",
            BOTTOM = "bottom",
            POSITION = "position",
            STATIC = "static",
            RELATIVE = "relative",
            AUTO = "auto",
            ZINDEX = "z-index";

    Ext.Element.addMethods({
    	/**
          * Gets the current X position of the element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
          * @return {Number} The X position of the element
          */
        getX : function(){
            return D.getX(this.dom);
        },

        /**
          * Gets the current Y position of the element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
          * @return {Number} The Y position of the element
          */
        getY : function(){
            return D.getY(this.dom);
        },

        /**
          * Gets the current position of the element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
          * @return {Array} The XY position of the element
          */
        getXY : function(){
            return D.getXY(this.dom);
        },

        /**
          * Returns the offsets of this element from the passed element. Both element must be part of the DOM tree and not have display:none to have page coordinates.
          * @param {Mixed} element The element to get the offsets from.
          * @return {Array} The XY page offsets (e.g. [100, -200])
          */
        getOffsetsTo : function(el){
            var o = this.getXY(),
            	e = Ext.fly(el, '_internal').getXY();
            return [o[0]-e[0],o[1]-e[1]];
        },

        /**
         * Sets the X position of the element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @param {Number} The X position of the element
         * @param {Boolean/Object} animate (optional) True for the default animation, or a standard Element animation config object
         * @return {Ext.Element} this
         */
        setX : function(x, animate){
    	    return this.setXY([x, this.getY()], this.animTest(arguments, animate, 1));
        },

        /**
         * Sets the Y position of the element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @param {Number} The Y position of the element
         * @param {Boolean/Object} animate (optional) True for the default animation, or a standard Element animation config object
         * @return {Ext.Element} this
         */
        setY : function(y, animate){
    	    return this.setXY([this.getX(), y], this.animTest(arguments, animate, 1));
        },

        /**
         * Sets the element's left position directly using CSS style (instead of {@link #setX}).
         * @param {String} left The left CSS property value
         * @return {Ext.Element} this
         */
        setLeft : function(left){
            this.setStyle(LEFT, this.addUnits(left));
            return this;
        },

        /**
         * Sets the element's top position directly using CSS style (instead of {@link #setY}).
         * @param {String} top The top CSS property value
         * @return {Ext.Element} this
         */
        setTop : function(top){
            this.setStyle(TOP, this.addUnits(top));
            return this;
        },

        /**
         * Sets the element's CSS right style.
         * @param {String} right The right CSS property value
         * @return {Ext.Element} this
         */
        setRight : function(right){
            this.setStyle(RIGHT, this.addUnits(right));
            return this;
        },

        /**
         * Sets the element's CSS bottom style.
         * @param {String} bottom The bottom CSS property value
         * @return {Ext.Element} this
         */
        setBottom : function(bottom){
            this.setStyle(BOTTOM, this.addUnits(bottom));
            return this;
        },

        /**
         * Sets the position of the element in page coordinates, regardless of how the element is positioned.
         * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @param {Array} pos Contains X & Y [x, y] values for new position (coordinates are page-based)
         * @param {Boolean/Object} animate (optional) True for the default animation, or a standard Element animation config object
         * @return {Ext.Element} this
         */
        setXY : function(pos, animate){
    	    var me = this;
            if(!animate || !me.anim){
                D.setXY(me.dom, pos);
            }else{
                me.anim({points: {to: pos}}, me.preanim(arguments, 1), 'motion');
            }
            return me;
        },

        /**
         * Sets the position of the element in page coordinates, regardless of how the element is positioned.
         * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @param {Number} x X value for new position (coordinates are page-based)
         * @param {Number} y Y value for new position (coordinates are page-based)
         * @param {Boolean/Object} animate (optional) True for the default animation, or a standard Element animation config object
         * @return {Ext.Element} this
         */
        setLocation : function(x, y, animate){
            return this.setXY([x, y], this.animTest(arguments, animate, 2));
        },

        /**
         * Sets the position of the element in page coordinates, regardless of how the element is positioned.
         * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
         * @param {Number} x X value for new position (coordinates are page-based)
         * @param {Number} y Y value for new position (coordinates are page-based)
         * @param {Boolean/Object} animate (optional) True for the default animation, or a standard Element animation config object
         * @return {Ext.Element} this
         */
        moveTo : function(x, y, animate){
            return this.setXY([x, y], this.animTest(arguments, animate, 2));
        },

        /**
         * Gets the left X coordinate
         * @param {Boolean} local True to get the local css position instead of page coordinate
         * @return {Number}
         */
        getLeft : function(local){
    	    return !local ? this.getX() : parseInt(this.getStyle(LEFT), 10) || 0;
        },

        /**
         * Gets the right X coordinate of the element (element X position + element width)
         * @param {Boolean} local True to get the local css position instead of page coordinate
         * @return {Number}
         */
        getRight : function(local){
    	    var me = this;
    	    return !local ? me.getX() + me.getWidth() : (me.getLeft(true) + me.getWidth()) || 0;
        },

        /**
         * Gets the top Y coordinate
         * @param {Boolean} local True to get the local css position instead of page coordinate
         * @return {Number}
         */
        getTop : function(local) {
    	    return !local ? this.getY() : parseInt(this.getStyle(TOP), 10) || 0;
        },

        /**
         * Gets the bottom Y coordinate of the element (element Y position + element height)
         * @param {Boolean} local True to get the local css position instead of page coordinate
         * @return {Number}
         */
        getBottom : function(local){
    	    var me = this;
    	    return !local ? me.getY() + me.getHeight() : (me.getTop(true) + me.getHeight()) || 0;
        },

        /**
        * Initializes positioning on this element. If a desired position is not passed, it will make the
        * the element positioned relative IF it is not already positioned.
        * @param {String} pos (optional) Positioning to use "relative", "absolute" or "fixed"
        * @param {Number} zIndex (optional) The zIndex to apply
        * @param {Number} x (optional) Set the page X position
        * @param {Number} y (optional) Set the page Y position
        */
        position : function(pos, zIndex, x, y){
    	    var me = this;

            if(!pos && me.isStyle(POSITION, STATIC)){
                me.setStyle(POSITION, RELATIVE);
            } else if(pos) {
                me.setStyle(POSITION, pos);
            }
            if(zIndex){
                me.setStyle(ZINDEX, zIndex);
            }
            if(x || y) me.setXY([x || false, y || false]);
        },

        /**
        * Clear positioning back to the default when the document was loaded
        * @param {String} value (optional) The value to use for the left,right,top,bottom, defaults to '' (empty string). You could use 'auto'.
        * @return {Ext.Element} this
         */
        clearPositioning : function(value){
            value = value || '';
            this.setStyle({
                left : value,
                right : value,
                top : value,
                bottom : value,
                "z-index" : "",
                position : STATIC
            });
            return this;
        },

        /**
        * Gets an object with all CSS positioning properties. Useful along with setPostioning to get
        * snapshot before performing an update and then restoring the element.
        * @return {Object}
        */
        getPositioning : function(){
            var l = this.getStyle(LEFT);
            var t = this.getStyle(TOP);
            return {
                "position" : this.getStyle(POSITION),
                "left" : l,
                "right" : l ? "" : this.getStyle(RIGHT),
                "top" : t,
                "bottom" : t ? "" : this.getStyle(BOTTOM),
                "z-index" : this.getStyle(ZINDEX)
            };
        },

        /**
        * Set positioning with an object returned by getPositioning().
        * @param {Object} posCfg
        * @return {Ext.Element} this
         */
        setPositioning : function(pc){
    	    var me = this,
    	    	style = me.dom.style;

            me.setStyle(pc);

            if(pc.right == AUTO){
                style.right = "";
            }
            if(pc.bottom == AUTO){
                style.bottom = "";
            }

            return me;
        },

        /**
         * Translates the passed page coordinates into left/top css values for this element
         * @param {Number/Array} x The page x or an array containing [x, y]
         * @param {Number} y (optional) The page y, required if x is not an array
         * @return {Object} An object with left and top properties. e.g. {left: (value), top: (value)}
         */
        translatePoints : function(x, y){
    	    y = isNaN(x[1]) ? y : x[1];
            x = isNaN(x[0]) ? x : x[0];
            var me = this,
            	relative = me.isStyle(POSITION, RELATIVE),
            	o = me.getXY(),
            	l = parseInt(me.getStyle(LEFT), 10),
            	t = parseInt(me.getStyle(TOP), 10);

            l = !isNaN(l) ? l : (relative ? 0 : me.dom.offsetLeft);
            t = !isNaN(t) ? t : (relative ? 0 : me.dom.offsetTop);

            return {left: (x - o[0] + l), top: (y - o[1] + t)};
        },

        animTest : function(args, animate, i) {
            return !!animate && this.preanim ? this.preanim(args, i) : false;
        }
    });
    })();