Returns the corresponding reply event descriptor if an Apple event is being handled on the current thread.
- macOS 10.3+
An Apple event is being handled on the current thread if
current does not return
nil otherwise. This descriptor, including any mutations, will be returned to the sender of the current event when all handling of the event has been completed, if the sender has requested a reply. The effects of retaining the descriptor are undefined; it may be copied, but mutations of the copy are not returned to the sender of the current event.