Hello

Is there any reason or logic for following behavior

Let's has TestControl.ascx


<ext:Window runat="server" Width="800" Height="500" Modal="True" Icon="Book" CloseAction="Destroy"
    Hidden="true" Title="User Search" Frame="False" Layout="fit" Controller="EDMSAdmin_User_UserSearchDialogController">

    <Items>
        <ext:Panel Frame="true" runat="server" Border="true">
            <LayoutConfig>
                <ext:HBoxLayoutConfig Align="Stretch" />
            </LayoutConfig>
            <Items>


                <ext:Panel runat="server" Title="Available Groups" Flex="1" Frame="False">

                    <LayoutConfig>
                        <ext:VBoxLayoutConfig Align="Stretch" />
                    </LayoutConfig>
                    <Items>
                        <ext:GridPanel runat="server" Reference="dgvAllGrid" Flex="1" AddPagingToolbar="false">

                            <ColumnModel>
                                <Columns>
                                    <ext:Column DataIndex="GroupName" Text="Name" Flex="1" />
                                </Columns>
                            </ColumnModel>
                            <SelectionModel>
                                <ext:CheckboxSelectionModel runat="server" Mode="Simple" />
                            </SelectionModel>
                        </ext:GridPanel>
                    </Items>
                </ext:Panel>


            </Items>
        </ext:Panel>
    </Items>

</ext:Window>
and following code:
   UserControl ctrl = (UserControl)LoadControl("~/TestControl.ascx");
  var jsConfig = ComponentLoader.ToConfig(ctrl, false);
The output of that is 

 "controller": "EDMSAdmin_User_UserSearchDialogController",
    height: 500,
    hidden: true,
    renderTo: Ext.getBody(),
    width: 800,
    "extend": "Ext.window.Window",
    items: [{
        border: true,
        frame: true,
        items: [{
            flex: 1,
            items: [{
                "addPagingToolbar": false,
                reference: "dgvAllGrid",
                xtype: "grid",
                flex: 1,
                columns: {
                    items: [{
                        flex: 1,
                        dataIndex: "GroupName",
                        text: "Name"
                    }]
                },
                selModel: Ext.create("Ext.selection.CheckboxModel", {
                    selType: "checkboxmodel",
                    mode: "simple"
                })
            }],
            layout: {
                type: "vbox",
                align: "stretch"
            },
            title: "Available Groups"
        }],
        layout: {
            type: "hbox",
            align: "stretch"
        }
    }],
    layout: "fit",
    closeAction: "destroy",
    title: "User Search",
    iconCls: "#Book",
    hidden: true,
    modal: true
now my questio is - why selmmodel is using 
 selModel: Ext.create("Ext.selection.CheckboxModel", {
                    selType: "checkboxmodel",
                    mode: "simple"
                })
rather then 

 selModel:  {
                    selType: "checkboxmodel",
                    mode: "simple"
                }
is there any way to configure that ?