bug#13623: 24.3.50; Redisplay issue with transient-mark-mode

[Eli Zaretskii]

> Date: Tue, 05 Feb 2013 16:07:47 +0400
> From: Dmitry Antipov <dmantipov@yandex.ru>
> CC: Lawrence Mitchell <wence@gmx.li>, 13623@debbugs.gnu.org
> 
> > Hm.  Although this is an obvious bug, are you sure that we must redisplay
> > the whole window even if the region doesn't span multiple lines? IIUC
> > it should be enough to redisplay the current line only.
> 
> E.g. something like attached. This is the revert of 111673 plus special
> treatment of single-line region.

If you customize the font of 'region' face, you will see that
additional lines are affected anyway.