Ext.net中的CheckboxSelectionModel默认单项不选

　　var membersm = new Ext.grid.CheckboxSelectionModel({
2   dataIndex:"memberid"
3   ,listeners:{'beforerowselect': function( SelectionModel, rowIndex, keepExisting,record ) {
4            if(record.data.memberstatus!='1'){   //用户状态不正常
5                Ext.Msg.alert("提示信息","此人是管理员,你无法修改!");
6               return false;  //不能进行选择
7            }else{  
8                return true;  
9            }
10         }}
11
12 });