itemsChangeEffect is a property of TileList and List, HorizontalList is a subclass of TileBase so it didn't get the property, you could patch it in, just grab the relevant code from TileList and paste it into a subclass of HorizontalList.
Weird, the page I linked contains this text (emphasis added)
Currently, data change effects are implemented for List and TileList (including HorizontalList)
But you're right, it doesn't work on HorizontalList. I changed the control to a TileList and the itemsChangeEffect property is now available but I can't get it to do anything. Ideally I'd like the old data to slide out and the new data to slide in, but just getting it to do anything would be good at this point.
Did you get this working? Let me know if you still need assistance, I haven't had a chance yet to dig into this one.
The documentation you were reading was from labs.adobe.com, which shouldn't be "trusted" for final feature sets. Refer to the documentation at http://livedocs.adobe.com/flex/3/langref/index.html
Message was edited by: Jay Proulx
No, I have been unable to get it to work on any kind of control.