allout-widgets-adjusting-message is a compiled Lisp function in `
Post MESSAGE when pending are likely to make a big enough delay.
If posting of the MESSAGE is warranted and there already is a
`current-message' in the minibuffer, the MESSAGE is appended to
the current one, and the previously pending `current-message' is
returned for later posting on completion.
If posting of the MESSAGE is warranted, but no `current-message'
is pending, then t is returned to indicate that case.
If posting of the MESSAGE is not warranted, then nil is returned.
`allout-widgets-adjust-message-size-threshold' for message
posting threshold criteria.