How to bind TreePanel value in DropDownField at GridPanel ?

[fsgprivate]

How to bind TreePanel value in DropDownField at GridPanel ?

I don't know how to bind DropDownField value in GridPanel, it can get value use Ext.encode(#{GridData}.getRowsValues, how do I do ?

[fsgprivate]

<ext:ComponentColumn
                                runat="server"
                                Editor="true"
                                DataIndex="DEPT_ID"
                                Text="管理机构" Width="200">
                                <Component>
                                    <ext:DropDownField ID="DeptId" runat="server" AllowBlank="false"
                                        Editable="false" Mode="ValueText">
                                        <Component>
                                            <ext:TreePanel ID="DeptTree" runat="server" UseArrows="true" AutoScroll="true" ContainerScroll="true" Height="250">
                                                <Listeners>
                                                    <Select Handler="this.dropDownField.setValue(record.data.id, record.data.text);" />
                                                </Listeners>
                                            </ext:TreePanel>
                                        </Component>
                                        <Listeners>
                                            <Expand Handler="this.component.getRootNode().expand(true);" Single="true" Delay="10" />
                                            <Render Handler="item.setValue(item.record.data.DEPT_ID, item.record.data.DEPT_ID);return 'fsss'"></Render>
                                        </Listeners>
                                    </ext:DropDownField>
                                </Component>
                                <Renderer Fn="translate"></Renderer>
                            </ext:ComponentColumn>

Is there some one know ?