bug#12419: Mouse click changes layout

[Drew Adams]

> For example, when resizing a frame, windows are resized symmetrically.
> That is, all windows shrink or grow proportionally to their 
> normal size.

Sounds reasonable.  But shouldn't it be a user choice (e.g. option)?  What if a
user wants some particular window's height (or width) to stay the same (assuming
there is enough space), while s?he changes the frame height (or width)?

Perhaps something akin to window dedication, to indicate that, as much as
possible, you want to keep the height or width of a particular window.

Or perhaps we could optionally let users keep just the selected window the same
size (as much as possible), when resizing the frame.  That would perhaps be
simpler than the suggestion above.

> This also means that, modulo some rounding errors, shrinking 
> a frame and enlarging it by the same amount will bring back
> the initial layout.

That sounds good.

> When dragging a divider, windows are resized asymmetrically, 
> that is we enlarge only the window we drag away from and
> shrink the windows on the other side.

That sounds normal, but what is the alternative - how could it be otherwise?

> Asymmetric resizing is not reversible, that is, dragging the
> divider back by the same amount will not necessarily reproduce the
> inital configuration.

I don't think that is what I see.  But I guess I don't understand what you're
saying.  Can you give an example, and contrast what happens in earlier Emacs
releases?

> This property makes asymmetric resizing unsuitable for
> resizing the minibuffer window where we eventually want
> to get back the initial configuration.