ExtJS4布局【转自MHZG.NET】
面板相当于一张干净的白纸，如果直接在上面添加内容，将很难控制面板中内容的显示位置，面板元素越多就越显得凌乱，所以需要在面板上划分不同的区域，将面板内容展示到希望的位置上。ExtJS通过提供多种布局类来为面板提供支持，主要包括如下10种：
   ContainerLayout（容器布局）
   FitLayout（自适应布局）
   AccordionLayout（折叠布局）
   CardLayout（卡片式布局）
   AnchorLayout（锚点布局）
   AbsoluteLayout（绝对位置布局）
   FormLayout（表单布局）
   ColumnLayout（列布局）
   TableLayout（表格布局）
   BorderLayout（边框布局）



Extjs4布局详解(一)—Fit布局


在Fit布局中，子元素将自动填满整个父容器。注意：在fit布局下，对其子元素设置宽度是无效的。如果在当前容器中存在多个子面板则只有第一个会被显示。典型的案例就是当客户要求一个window或panel中放置一个GRID组件，grid组件的大小会随着父容器的大小改变而改变。

示例代码：

  

 var myData = [
            ['3m Co',                               71.72, 0.02,  0.03,  '9/1 12:00am'],
            ['Alcoa Inc',                           29.01, 0.42,  1.47,  '9/1 12:00am'],
            ['Altria Group Inc',                    83.81, 0.28,  0.34,  '9/1 12:00am'],
            ['American Express Company',            52.55, 0.01,  0.02,  '9/1 12:00am'],
            ['American International Group, Inc.',  64.13, 0.31,  0.49,  '9/1 12:00am'],
            ['AT&T Inc.',                           31.61, -0.48, -1.54, '9/1 12:00am'],
            ['Boeing Co.',                          75.43, 0.53,  0.71,  '9/1 12:00am'],
            ['Caterpillar Inc.',                    67.27, 0.92,  1.39,  '9/1 12:00am'],
            ['Citigroup, Inc.',                     49.37, 0.02,  0.04,  '9/1 12:00am'],
            ['E.I. du Pont de Nemours and Company', 40.48, 0.51,  1.28,  '9/1 12:00am'],
            ['Exxon Mobil Corp',                    68.1,  -0.43, -0.64, '9/1 12:00am'],
            ['General Electric Company',            34.14, -0.08, -0.23, '9/1 12:00am'],
            ['General Motors Corporation',          30.27, 1.09,  3.74,  '9/1 12:00am'],
            ['Hewlett-Packard Co.',                 36.53, -0.03, -0.08, '9/1 12:00am'],
            ['Honeywell Intl Inc',                  38.77, 0.05,  0.13,  '9/1 12:00am'],
            ['Intel Corporation',                   19.88, 0.31,  1.58,  '9/1 12:00am'],
            ['International Business Machines',     81.41, 0.44,  0.54,  '9/1 12:00am'],
            ['Johnson & Johnson',                   64.72, 0.06,  0.09,  '9/1 12:00am'],
            ['JP Morgan & Chase & Co',              45.73, 0.07,  0.15,  '9/1 12:00am'],
            ['McDonald\'s Corporation',             36.76, 0.86,  2.40,  '9/1 12:00am'],
            ['Merck & Co., Inc.',                   40.96, 0.41,  1.01,  '9/1 12:00am'],
            ['Microsoft Corporation',               25.84, 0.14,  0.54,  '9/1 12:00am'],
            ['Pfizer Inc',                          27.96, 0.4,   1.45,  '9/1 12:00am'],
            ['The Coca-Cola Company',               45.07, 0.26,  0.58,  '9/1 12:00am'],
            ['The Home Depot, Inc.',                34.64, 0.35,  1.02,  '9/1 12:00am'],
            ['The Procter & Gamble Company',        61.91, 0.01,  0.02,  '9/1 12:00am'],
            ['United Technologies Corporation',     63.26, 0.55,  0.88,  '9/1 12:00am'],
            ['Verizon Communications',              35.57, 0.39,  1.11,  '9/1 12:00am'],
            ['Wal-Mart Stores, Inc.',               45.45, 0.73,  1.63,  '9/1 12:00am']
        ];
    var store = Ext.create('Ext.data.ArrayStore', {
        fields: [
           {name: 'company'},
           {name: 'price',      type: 'float'},
           {name: 'change',     type: 'float'},
           {name: 'pctChange',  type: 'float'},
           {name: 'lastChange', type: 'date', dateFormat: 'n/j h:ia'}
        ],
        data: myData
    });
    Ext.define('DataWindow',{
        extend : 'Ext.window.Window',
        title : 'MHZG.NET---Fit布局示例代码',
        width:550,
        layout : 'fit',
        items : {
            xtype : 'gridpanel',
            s