bug#14170: 24.3; linum won't create all overlays after a folding

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> > It crossed my mind, but I didn't like the idea, as it also removes
>> > "good" fortification.  I suppose this could be of little consequence.
>> I don't know what you mean by "removes good fontification".
> Actually you've said it in a comment:
> (remove-overlays start end 'nlinum t)
> ;; Warn jit-lock that this part of the buffer is not done any
> ;; more.  This has the downside that font-lock will be re-applied
> ;; as well.  But jit-lock doesn't know how to (and doesn't want
> ;; to) keep track of the status of its various
> ;; clients independently.
> (put-text-property start end 'fontified nil)

Oh, that's what you meant by "remove".  Right, it flushes fontification
which did not need to be flushed, but that can be recomputed.
Of course, the overall impact on performance could be a concern,
although it's unclear how important that would be.  Based on the
experience that having many overlays isn't nearly as bad as expected,
the nlinum--ol-count limit could be pushed much higher than 100, thus
reducing the potential performance impact of "removing good
fontification" correspondingly.


        Stefan