bug#56393: Actually fix the long lines display bug

[Gerd Möllmann]

Gregory Heytings <gregory@heytings.org> writes:

>> WDYT about marking buffers that don't want auto narrowing?  Or the
>> opssite, mark buffers that want it?
>>
>
> One of the explicit aims when designing that feature was that it
> should be as transparent as possible.  And it is: only a few selected
> places in xdisp.c see its effect.

Okay.

> That being said, you can do what you want nonetheless: if you
> (setq-local long-line-threshold nil) the optimizations will never be
> used (in that buffer), if you (setq-local long-line-threshold 0) the
> optimizations will always be used (in that buffer).
>
> Adding code to expose the feature further to Lisp would be (IMO) a
> mistake.

Understood.