/// <summary>
/// Raises the <see cref="E:PreRender"/> event.
/// </summary>
/// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
// Storeave the filter criteria of the list in Page's viewstate.
// This enables post-back events such as sorting and paging to operate on the correct data source.
ViewState["FilterCriteria"] = FilterCriteria.Select(c => c.ToString()).ToArray();
GetGridList().Perform(g => g.Attributes["CurrentSort"] = SortExpression);
}