bug#12419: Mouse click changes layout

[martin rudalics]

>> That all windows on the other side get resized proportionally.
>
> How is that different from "shrink the windows on the other side"?  I'm 
guessing
> that shrink them, but not proportionately?

Yes.  Shrink (or grow) the ones adjacent to an edge first.

> I see.  In previous releases when you drag one mode line, only the adjacent
> window shrinks.  And that corresponds exactly (AFAICT) to the opposite action 
of
> dragging the mode line back again.  So previously the opposite drag action was
> symmetric to the initial drag action.  Now it is not.
>
> Can we (and then should we) make this change in behavior optional (for the
> user)?

If you have a copy of Emacs 19 or 20 around you will notice that other
windows did shrink too.  The "shrink only the adjacent window" behavior
you mention was introduced together with `adjust-window-trailing-edge'.
But this function is not very suitable for the minibuffer.

>> Now set `resize-mini-windows' to nil and drag the bottom modeline.
>> All windows get resized proportionally in both directions.
>
> Not with a standalone minibuffer frame.  At least I see no change in behavior,
> whatever the value of `resize-mini-windows'.

You need a "normal" frame with a minibuffer for this.

> 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.

> 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.

martin