bug#31325: 27.0.50; PROPOSAL: introduce a new function to recenter without redisplaying the frame

[John Shahid]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: John Shahid <jvshahid@gmail.com>
>> Cc: rudalics@gmx.at, 31325-done@debbugs.gnu.org, monnier@iro.umontreal.ca
>> Date: Sun, 01 Jul 2018 16:54:53 +0000
>>
>> It just occurred to me that this change will break backward
>> comparability for those who bind some key to the `recenter' command,
>> since now the second argument will always be nil and thus won't
>> redisplay.  Should we also change the interactive form of recenter to
>> use "p" for the second argument?  That way the second arg is never nil
>> when used interactively.
>
> I think you are right.
>
> Alternatively, we could simply make 'recenter' behave specially in
> interactive invocations.  But in any case, incompatible changes in
> behavior are bad, and should be avoided.

I am happy to make the change. Should we just revert this patch and
instead of adding a new argument change the behavior of`recenter' to
redraw if called interactively ?

How can we determine from C whether the function is called interactively
? Is it ok to use `called-interactively-p' ?