protected override void OnInitialized()
        {
            if (PagerState == null)
            {
                throw new InvalidOperationException("DataPager must be child of DataGrid");
            }

            // copy defaults to state
            PagerState.Attach(1, PageSize);
            PagerState.PropertyChanged += OnStatePropertyChange;
        }
        protected override void OnInitialized()
        {
            if (PagerState == null)
            {
                throw new InvalidOperationException("DataSizer requires a cascading parameter PagerState.");
            }

            // copy defaults to state
            PagerState.Attach(1, PageSize);
            PagerState.PropertyChanged += OnStatePropertyChange;
        }