easyui multiple combogrid被取消选中的行还是会显示出来

Question

    被取消选中的行还是会显示出来？以下是我的代码
        <select class="easyui-combogrid" style="width:250px" data-options="
        panelWidth: 500,
        multiple: true,
        idField: 'ProblemId',
        textField: 'Title',
        url: 'datagrid_data1.json',
        method: 'get',
        columns: [[
            {field:'ck',checkbox:true},
            {field:'ProblemId',title:'id',width:80},
            {field:'Title',title:'标题',width:120}

        ]],
        fitColumns: true
    " id="cg">
        </select>
         <input class="easyui-textbox" colfield="ProblemIDstr" name="ProblemIDs_name"  id="ProblemIDs" value="" editable="false"
               style="width: 310px"/>
               <Script>
              $('#cg').combogrid({
    onSelect: function (index,row) {              //选中处理

       var val = $('#cg').combogrid('getValues').join(',');
        $("#ProblemIDs").textbox("setValue", val);
    }
});</script>