The ElementAgenda provides a collection of elements. It's useful to enumerate the collection to harvest information. However, the enumeration methods (e.g. _OnElementModify()) pass a non-const EditElementHandle.
ElementAgenda
_OnElementModify()
const
EditElementHandle
When harvesting information, it would be useful to have a const enumeration method (e.g. _OnElementPeek()) that passes an ElementHandle. Currently we have to return an unintuitive !SUCCESS from the enumeration methods to ensure that the element is not modified or removed from the agenda.
_OnElementPeek()
ElementHandle
!SUCCESS