Re: Single process output reading

[Richard Stallman]

    IMO a better way would be to allow restricting accept-process-output to
    just a single process output reading.  Then the speech output system,
    aware of possible consequences of advising 'message' etc., could invoke
    accept-process-output in the restricted form, without the danger of
    unwanted side effects.

I think it would be reasonable to provide a way to tell
wait_reading_process_output to ignore certain processes and read from
certain other processes.  I worry about the idea of not running timers,
though, and that seems unnecessary for what you need.  I think it
would be better to implement the feature so that timers do run.

I think it would be better to clean up the calling conventions
of wait_reading_process_output rather than try to squeeze everything
into the existing argumemts.