ExtJS GridPanel分页、添加、删除、修改
CheckboxSelectionModel是grid的选择模式
删除行应该使用grid的store.remove方法。
BranchGrid=Ext.extend(Ext.grid.GridPanel,{  //从Ext.grid.GridPanel中继承
    AddBranch:null, //声明Window组件
    constructor:function(){//构件器
        this.AddBranch=new AddBranchWindow();//创建 window组件
        this.store=new Ext.data.Store({  //数据源
////                autoLoad:true,//为“true”自动加载数据
                url:"GetBranchGrid.ashx",//从那里获得数据
                reader:new Ext.data.JsonReader({
                        root:"data",
                        totalProperty:"count"
                    },[ //设置格式
                        {name:"ID",type:"int"},
                        {name:"brname",type:"string"}
                ])
            });
        BranchGrid.superclass.constructor.call(this,{ //对父类初始化
            title:"部门信息",
            renderTo:Ext.getBody(),
            width:410,
            height:350,
            store:this.store,   //设置数据源
            selModel:new Ext.grid.RowSelectionModel({ 
                singleSelect:true //定义选择模式”singleSelect“为ture时只能单选，默认为false
            }),
            columns:[new Ext.grid.RowNumberer(),{
                header:"部门编号",
                dataIndex:"ID",
                align:"center"
            },{
                header:"部门名称",
                dataIndex:"brname"
            }],
            loadMask:{msg:"数据加载中...."},
            tbar:[{
                    text:"添加",