bug#15899: 24.3.50; regression: `region' overlay is lower priority than default

[Eli Zaretskii]

> Date: Thu, 14 Nov 2013 14:57:14 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> 
> In Emacs 24.3, if you highlight some text with an overlay, without
> specifying any priority for the overlay, that overlay will be lower
> priority than the `region' face overlay that is used to select text for
> the region.
> 
> In this build, the region overlay is of lower priority, so the other
> overlay hides the region overlay.

In Emacs 24.3, the region highlight was not done by an overlay, but by
special code in C.  Now it is an overlay, so the issue of priority
creeps in.

> Do the same thing in Emacs 24.3 - no bug there.  Dunno when the
> regression started.

It started when Stefan made the region use an overlay.