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

[Gregory Heytings]

> > By definition, this cannot be unsafe for any buffer, except those in 
> > which long_line_optimizations_p is set.  So the worst that could 
> > possibly happen is that Emacs would hang in some buffers in which 
> > long_line_optimizations_p is set, which is not a regression: Emacs 28 
> > and earlier would have hanged under the same conditions.
>
> Given the fanfare we announced the solution to long-line problems, the 
> above is precisely the definition of "not safe" from my POV.

We never announced that all possible problems in such buffers would be 
solved.  In fact, the NEWS entry explicitly mentions that slowdowns are 
still possible because of minor or major modes, and contains instructions 
to gradually disable minor and major modes when such problems happen.

My preference is still to remove that feature.

> I'm sorry I have to insist, but does this mean you will be able to fix 
> these documentation issues in less than a week?  I don't think I can 
> wait any longer than that.

I'll do that in less than a week, after hearing your final verdict, if you 
decide that it should not be removed.