I always use display format, so I did not noticed this.
I can't answer your question ("why has changed?") but:
a) is this a problem of IB_Edit, or a general IBO issue?
b) have you compared working code with the new one? No comments in the source about this?
c) instead of writing code to revert to the old behaviour, why not define DisplayFormat at domain/ib_connection level?
d) I love having date formatted in a different way than when they are edited. For instance, I edit 99/99/99 and often format dd/mm/yyyy ddd

anyway, I'm happy you are upon IBO code again :))
regards
Marco Menardi