Re: Nested display strings

[Eli Zaretskii <eliz@gnu.org>]

> From: "Drew Adams" <drew.adams@oracle.com>
> Date: Sat, 23 Apr 2011 13:31:47 -0700
> 
> Don't `display' and `priority' get along well, or can't they be be made to get
> along?
> 
> We have two overlapping overlays here, and the usual way to determine what
> happens when overlays overlap is by looking at their `priority' values (among
> other things).

In the example that started this thread, there were no priorities at
all.  The question is, whether the behavior in that case is correct or
not.

But even if different priorities were involved, how do they help
resolve the issue with overlays that have `display' property whose
value is a string or an image?  These overlay properties _replace_ the
buffer text, not determine how to display the buffer text.  If the two
overlays were covering the same range of buffer positions, then we
could expect that the overlay with the higher priority would "win".
But what to do in the case I presented, where one of the overlays
covers only a subset of positions covered by the other?  How can
priorities help in that case?  If the "shorter" overlay has a higher
priority, what to display instead of the characters covered only by
the "longer" one?  Either nothing or you get the duplicate display of
STRING1 again.  Both alternatives look bad.

> If `display' and `priority' can be made to cooperate then that would be good.

I don't see how could they; see above.