/// <summary>
/// Saves any state that was modified after the TrackViewState method was invoked
/// 并在SaveViewState之前，将ViewState中所有IStateManager类型项转换为可序列化的ViewSateItemInternal类型项
/// 以及在SaveViewState之后，将ViewState中所有ViewSateItemInternal类型项恢复成IStateManager类型项
/// </summary>
/// <returns>返回服务器控件的当前视图状态</returns>
/// <remarks>
/// Saves any state that was modified after the TrackViewState method was invoked
/// 并在SaveViewState之前，将ViewState中所有IStateManager类型项转换为可序列化的ViewSateItemInternal类型项
/// 以及在SaveViewState之后，将ViewState中所有ViewSateItemInternal类型项恢复成IStateManager类型项
/// </remarks>
protected override object SaveViewState()
{
ViewState.PreSaveViewState();
object o = base.SaveViewState();
ViewState.AfterSavedViewState();
return(o);
}