No slight intended, @meredydd. I was thinking more about events in general, e.g. for an event provided by a Custom Component. In that case, there may be no up-to-date documentation, or no documentation at all.
Event-handlers can also be invoked directly by Python code. In this case, the caller may be passing additional named arguments, to give the handler a more complete picture of the situation. Conversely, it might be failing to pass the usual parameters! Most likely, neither situation will be documented.
print(event_args), used sparingly, can be very revealing in all of these cases. I’m very glad you guys made it possible.