I ran into a problem with expanders not showing the contents of a child collection.  I found that when a child collection is cleared out the grid re-evaluates which FieldLayout to use.  Since the contents of the child collection is now empty it has no data type to check against.  I think it then uses the type of collection to check for the FieldLayout to use.  The problem happens when the collection’s type is a base type, but the contents end up being a collection of types derived from the base type.  This causes the grid to not find a FieldLayout to use and creates an empty one.  From there on out, the expanders no longer work.  I’ve created a test app which shows this condition and attached it.  I’ve gotten around this issue by hooking into the AssigningFieldLayoutToItem handler and forcing the FieldLayout.  Is there a better solution that this?

Thanks

Dan