bug#56682: feature/improved-locked-narrowing 9dee6df39c: Reworked locked narrowing.

[Stefan Monnier]

>> A function/macro to check that could indeed be added, its body would be:
>> 
>> (save-restriction (widen) (buffer-narrowed-p))
>
> We should add it and document it, but I'm surprised that there's no
> easier way.  One problem with the above is that it could cause a more
> thorough redisplay because it fiddles with buffer restrictions.

Seeing how `buffer-narrowed-p` is not used very often, I'm not
too worried.  Even more so given that the redisplay does try to notice
when the restriction has been modified temporarily but "reset" to its
original value since then.


        Stefan