async Task OnDrag(MouseEventArgs e)
{
var Rect = await GetRect(StartPoint, e.GetPosition(Grid));
if (IsDragging)
{
Selection.Set(Rect);
Select(ItemsControl, new Rect(ScrollContentPresenter.TranslatePoint(Selection.TopLeft, ScrollContentPresenter), ScrollContentPresenter.TranslatePoint(Selection.BottomRight, ScrollContentPresenter)));
Scroll(e.GetPosition(ItemsControl));
}
}
