Expand all items on page load

[A]

Anyone,
I am using a RadGrid that contains one DetailTable as in the below code. I am binding the datasource for the grid in the NeedDataSource Event (need to do this way). I need to Expand all the items to show up the details table, on the page load (first time load); i am not sure when to expand the items. I tried doing it on the NeedDataSource event, but it doesn't work.

Please note: I have a asp button on the page for collapsing all the grid items. So i am unable to use the PreRender event as well. 

Can someone please suggest how do i go about this scenario?

<telerik:RadGrid ID="RadGrid1" runat="server" AutoGenerateColumns="False"

        AllowSorting="False" AllowMultiRowSelection="False" AllowPaging="False" OnNeedDataSource="RadGrid1_NeedDataSource"

        OnDetailTableDataBind="RadGrid1_DetailTableDataBind" Skin="Default">       

        <MasterTableView DataKeyNames="col1" ExpandCollapseColumn-ButtonType="PushButton">

            <DetailTables>

                <telerik:GridTableView Name="detailGrid" Width="95%" BorderStyle="Solid" BorderWidth="1px" HorizontalAlign="Center">

                    <Columns>

                        <telerik:GridBoundColumn HeaderText="col1" HeaderButtonType="TextButton" DataField="col1" />

                        <telerik:GridBoundColumn HeaderText="col2" HeaderButtonType="TextButton" DataField="col2" />                        

                    </Columns>

                </telerik:GridTableView>

            </DetailTables>

            <Columns>

.....



[A]

Thanks! I found the solution. By checking (!IsPostback) on prerender event, solves my purpose!