Thank you for the feedback, @GKing.
You’re right. There is an issue in v5.0 that is related to the new Shapefile.Selectable attribute (being able to select multiple layers concurrently by setting their Selectable property = True).
However, the behavior already existed in the case of single-layer selection. If you specifed a layer handle in the ChooseLayer event, even in v4.9, AND any shapes were selected, the SelectionChanged event was raised, but the SelectBoxFinal event was not raised. It was only raised if you did not specify a layer handle in the ChooseLayer event OR no shapes were selected.
Even so, a bug now exists in v5.0, such that the SelectBoxFinal event is not raised in either case.
Please consider the following, and feel free to advise (I am including @pmeems in the discussion).
Note that historically, the SelectBoxFinal event was not raised if a layer was marked for selection AND shapes were actually selected.
Based on the documentation, if you do not specify a layer handle in the ChooseLayer event, the operation will not be performed. It does not indicate whether or not the SelectBoxFinal event should still be raised.
The documentation for the SelectBoxFinal event puts no conditions on whether or not it should be raised.
QUESTION: Should the SelectBoxFinal event always be raised?, or as in the past, only when no shapes were actually selected?