Subject: bug#78120: 31.0.50; Calendar is not reliable with its marking

From: Eli Zaretskii <[email-masked]>
Date: Mon, 05 May 2025 14:28:18 +0300

> From: Michael Heerdegen <[email-masked]>
> Cc: [email-masked],  [email-masked]
> Date: Mon, 05 May 2025 02:45:37 +0200
> 
> > Both overlays have the same (unspecified) priority, so which one of
> > them "wins" depends on many factors, including the exact memory layout
> > of the Emacs session.  The latter changes each time you press 'm', so
> > you sometimes see one or the other face.
> 
> Plausible. (Would it be thinkable to make the behavior deterministic?)

It's deterministic.  But the factors affecting determinism are
sometimes not deterministic enough ;-)

> > The solution is to decide which overlay should "win" in this case, and
> > give one of them higher or lower priority, as appropriate.
> 
> This might not be easy, though (I mean the "appropriate" part), since
> there are multiple different places in diary-lib that mark dates.  And
> of course there is also the problem of multiple matches of one source,
> for example, multiple sexps matching the date that want to draw
> different faces.

So Someone™ should take a look at the faces and decide which one of
them is more important, or at least post the list here so we could
discuss based on that list.

Alternatively, we could change the default definition of one or more
faces, so that they don't conflict.  For example, instead of defining
only the foreground color, we could define the background or
underline, or weight or the box attributes.