Re: Display problems with 'before-string in overlay

[Kim F. Storm]

Richard Stallman <address@hidden> writes:

>     > Can you track down the bug report(s) which lead up to the fix I
>     > installed, so you can confirm that your change also fixes the old 
> bug(s).
>     > It must be close to the date in the ChangeLog.
>
>     IIRC, there were quite a lot of test cases - combining before and
>     after strings as well as compositions, so I really feel bad about
>     touching this now.
>
> If you make a change that only takes action in the bug case,
> you can be sure you are not breaking any other case.

Pardon me, but that's nonsense.

How can I be sure that the change "only takes action in the bug case" ?

How can I be sure that _any_ change in redisplay will not have
unexpected side-effects ... in my experience, most "first attempt"
redisplay changes aimed at fixing corner-case bugs have unexpected
side-effects.  

Redisplay is just so damn complicated that I would never use the word
"sure" in that context.

-- 
Kim F. Storm <address@hidden> http://www.cua.dk