<asp:Panel ID="ModalDialog" runat="server" Style="display: none;">
<asp:UpdatePanel runat="server" ID="UpdatePanel" ChildrenAsTriggers="true" UpdateMode="Conditional">
    <ContentTemplate>
 <asp:GridView runat="server" ID="ResultGridTest" AutoGenerateColumns="true" ShowHeader="true" Width="100%" />
    </ContentTemplate>
    <Triggers>
    <asp:PostBackTrigger ControlID="ResultGridTest" />
</Triggers>
</asp:UpdatePanel>
</asp:Panel>

$j("#ModalDialog").dialog("open");

protected void GridViewControl_DataBindGridView(object sender, PassSelectedValuesEventArgs<Model> e)
{
    ResultGridTest.DataSource = e.SelectedItems;
    ResultGridTest.DataBind();
}