That's sort of misconception about ArrayCollection. It is not a collection, it misses "View" part in the name, but if you'll look at inheritance chain, then you'll see it is a view - it's basically the same as ListCollectionView. Another thing about ArrayCollection or ListCollectionView is that it is very slow (because it is a mediator between the real collection and your iterating / sorting algorithm). I think the idea behind having a collection view was to have an adapter between several kinds of AS3 "native" collections and the UI. It was not meant to be a collection. It just got a strange name for the reason we will not know :) Depends on your filtering algorithm, I'd either filter an array, or try writing RBTree and then reset the source in the collection view. Sorting / filtering by using some ListCollectionView / Sort methods will be very slow anyway.
Best. Oleg
