Instructs a System.Web.UI.WebControls.SubMenuStyle object contained by the System.Web.UI.WebControls.SubMenuStyleCollection collection to record its entire state to view state.
The SubMenuStyleCollection.SetDirtyObject(object) method is called internally by the System.Web.UI.IStateManager.SaveViewState, SubMenuStyleCollection.Add(SubMenuStyle), and SubMenuStyleCollection.Insert(int, SubMenuStyle) methods.