Ext EditorGridPanel里面用combobox怎么才能接受非上拉框的内容

Ext EditorGridPanel里面用combobox如何才能接受非下拉框的内容?
不知道我的描述明白不.我现在的定义是如下,出现的问题是.我只能选下拉框里面有的东西,能不能让此combobox能输入下拉列表不存在的东西.应该怎么做?谢谢
最好有简单的例子..再次感谢

JScript code

{    header: "供应商",    width: 250,     dataIndex: 'provider',    editor: new Ext.form.ComboBox({         id:'prvcombobox',        typeAhead: true,        listClass: 'x-combo-list-small',        emptyText:'请选择',         displayField:'provider',        selectOnFocus:true,         triggerAction: 'all',         store: store,         lazyRender:true    })}

JScript code

    listeners:{        focus:function(obj){            var sm = oGrid.getSelectionModel();            var rd = sm.getSelected();            this.rdid = rd.id;        },        change:function(obj){            var val = obj.getRawValue();            var rd = oStore.getById(this.rdid);            rd.set("provider", val);            getDetail(val, this.rdid);        }    },
[解决办法]
我是这么做的  
JScript code
var strGoupSelectBox=new Ext.form.ComboBox({        typeAhead: true,        triggerAction: 'all',        lazyRender: true,        transform:'prot_group',        // -----------------------add by YDF at 2009-9-18 17:33:59        id:'goupSelectBox',        name:'goupSelectBox',        valueField:"keyid",      // 提交表单时，下拉框的值        displayField:'name',     // 显示在页面上下拉框的值        emptyText:'请选择..',        editable:false,        store: new Ext.data.JsonStore({          // 动态从后台提取数据并填充到 ComboBox          autoLoad:true,          fields: ['keyid', 'name'],          url: '../data/sample_application_manager_getgroup_get_json.jsp',          mathod:'post'        }),        listeners:{            select:function(strGoupSelectBox,record,index){                var groupValue = strGoupSelectBox.value;                                alert(groupValue);                            }}    });