Re: redisplay-dont-pause is not mentioned in the Emacs manual

[Richard Stallman]

    To repeat, (B) says:

      (B) Don't _interrupt_ redisplay once it has started.

    And this definitely _is_ (part of) what you get by setting 
redisplay_dont_pause.

It is part of what you get, but now it is no longer the whole of what
you get.

Perhaps we should undo the recent change in sit-for.
I don't remember the specific case for which we made it.
If it was one specific caller that needed another facility,
let's make (sit-for -1) do this, as someone else suggested.