别人写的jslayout插件 可以分为 north、center、south
/*!
 * jLayout JQuery Plugin v0.17
 *
 * Licensed under the new BSD License.
 * Copyright 2008-2009 Bram Stein
 * All rights reserved.
 */
/*global jQuery jLayout*/
if (jQuery && jLayout) {
    (function ($) {
        /**
         * This wraps jQuery objects in another object that supplies
         * the methods required for the layout algorithms.
         */
        function wrap(item, resize) {
            var that = {};

            $.each(['min', 'max'], function (i, name) {
                that[name + 'imumSize'] = function (value) {
                    var l = item.data('jlayout');
                    
                    if (l) {
                        return l[name + 'imum'](that);
                    } else {
                        return item[name + 'Size'](value);
                    }
                };
            });

            $.extend(that, {
                doLayout: function () {
                    var l = item.data('jlayout');
                    
                    if (l) {
                        l.layout(that);
                    }
                    item.css({position: 'absolute'});
                },
                isVisible: function () {
                    return item.isVisible();
                },
                insets: function () {
                    var p = item.padding(),
                        b = item.border();

                    return {
                        'top': p.top, 
                        'bottom': p.bottom + b.bottom + b.top, 
                        'left': p.left, 
                        'right': p.right + b.right + b.left
                    };
                },
                bounds: function (value) {
                    var tmp = {};

                    if (value) {
                        if (typeof value.x === 'number') {
                            tmp.left = value.x;
                        }
                        if (typeof value.y === 'number') {
                            tmp.top = value.y;
                        }
                        if (typeof value.width === 'number') {
                            tmp.width = (value.width - (item.outerWidth(true) - item.width()));
                            tmp.width = (tmp.width >= 0) ? tmp.width : 0;
                        }
                        if (typeof value.height === 'number') {
                            tmp.height = value.height - (item.outerHeight(true) - item.height());
                            tmp.height = (tmp.height >= 0) ? tmp.height : 0;
                        }
                        item.css(tmp);
                        return item;
                    } else {
                        tmp = item.position();
                        return {
                              'x': tmp.left,
                            'y': tmp.top,
                            'width': item.outerWidth(false),
                            'height': item.outerHeight(false)
                        };
                    }
                },
                preferredSize: function () {
                    var minSize,
                        maxSize,
                        margin = item.margin(),
                        size = {width: 0, height: 0},
                        l = item.data('jlayout');

                    if (l && resize) {
                        size = l.preferred(that);

                        minSize = that.minimumSize();
                        maxSize = that.maximumSize();

                        size.width += margin.left + margin.right;
                        size.height += margin.top + margin.bottom;

                        if (size.width &l