bug#37700: 27.0.50; undo mouse-drag-and-drop-region ineffective

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Fri, 11 Oct 2019 14:51:01 +0200
> Cc: 37700@debbugs.gnu.org
> 
> 11 okt. 2019 kl. 14.19 skrev martin rudalics <rudalics@gmx.at>:
> > 
> > I suppose this the effect of undo working on the active region only.
> > A very nasty invention.  Try deactivating the region right after 3.
> 
> Right, thank you. I wonder if anything would break if that were changed.
> 
> Proof-of-concept patch attached. (Manual and NEWS changes not included.) It 
> does solve this particular problem.

Given that the region can be easily deactivated, I'm not sure I see
the sense in introducing options that selectively disable
region-sensitive behavior of specific commands.