bug#12419: Mouse click changes layout

[Drew Adams]

> If you have a copy of Emacs 19 or 20 around you will notice that other
> windows did shrink too.

No, I don't see that in Emacs 20 (I don't have 19).  I not only have a copy of
it hanging around, I use it much of the time!

> The "shrink only the adjacent 
> window" behavior you mention was introduced together with 
> `adjust-window-trailing-edge'.

Maybe, but in Emacs 20 I still see only the adjacent window shrink.  I'm on MS
Windows - dunno whether that make a difference.

GNU Emacs 20.7.3 (i386-*-nt5.1.2600) of Thu Dec 21 2000 on buffy

> But this function is not very suitable for the minibuffer.

>  > Consider proposing something for emacs-devel to discuss.  
>  > Was the change in behavior from Emacs 23 to 24 (the change
>  > made so far) ever discussed?
> 
> Partially.  Most of them were the results of attempting to fix errors.
> But I have to admit that I never understood the old code 
> completely so I couldn't even tell what has changed and how.

It would be good to present the alternative behaviors to people in emacs-devel
(and maybe even help-gnu-emacs), so they can make an informed choice.  And it
might be good to let end users have a choice (e.g., via an option), if that's
feasible.

>  > Personally I don't care much, since I don't split windows 
>  > that much.  But this sounds like something that affects lots
>  > of users, and perhaps there should be some discussion about it.
> 
> There should have been more testing before the release.  But I wasn't
> very good at advertising my branch then.

It's not likely that a branch will be tried by many Windows users who don't
build Emacs themselves.

Before inclusion in a release, a change should be available in a pretest
(prerelease version), and users can test it there.  But perhaps there was not
enough pretest time.  I believe that pretests used to be longer in the old days.

For another thing, users of a pretest should be informed (at least via NEWS, and
preferably on emacs-devel by anyone who wants something specific tested during
pretest) about new features to be tested.