// move the item within its group
private void MoveWithinSubgroup(object item, CollectionViewGroupInternal group, IList list, int oldIndex, int newIndex)
{
if (group.Move(item, list, ref oldIndex, ref newIndex))
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Move, item, newIndex, oldIndex));
}
}
