bug#25978: 25.1; Message from `text-scale-adjust' is shown in other frames too

[Eli Zaretskii]

> Date: Mon, 6 Mar 2017 08:52:42 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 25978@debbugs.gnu.org
> 
> > As long as "C-x C--" uses 'message' to display these instructions,
> > nothing can be done, because what you see is the usual behavior of
> > messages displayed in the echo area: they follow the selected frame.
> > 
> > Perhaps the frame-switch event should simply empty the echo area.
> > Patches to that effect are welcome.
> 
> Frame-switch should not systematically empty the echo area, IMO.

Of course not.  I meant only in this specific case.  IOW, set things
up in text-scale-adjust so that the echo area is emptied when frame is
switched after displaying this particular message.