Re: Layered display API

[Eli Zaretskii]

> Date: Thu, 14 Aug 2014 17:12:35 +0400
> From: Dmitry Gutov <address@hidden>
> CC: address@hidden, address@hidden
> 
> >> Why use the special new property, then? Just put a new overlay over it.
> >> If it also has `display' and higher priority, it would take over.
> >
> > Because you want to get priority not only over other overlays, but
> > also over display properties and maybe other things.
> 
> Doesn't any overlay's `display' get priority over text's `display'?

I don't remember, but if it does, it's an implementation detail
subject to change without notice.

> If I want to get priority over "maybe other things", the first problem 
> would how to know the list of all those things, and to retrieve the text 
> that gets displayed in stead of each of those things. Which would be, 
> again, reimplementing the display engine.

This property we are discussing (that doesn't yet exist) will be acted
upon by the display engine.  The display engine always knows what
"things" are there at point, and the supporting logic for this
property will cause the display engine to ignore all the other
"things" and display only the overlay that has this property.  At
least that's the theory.