bug#23478: 25.0.93; Mouse region selection asymmetry

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: npostavs@users.sourceforge.net,  23478@debbugs.gnu.org
> Date: Mon, 04 Jul 2016 10:45:43 +0200
> 
> > Let's make one step back and describe the exact change in behavior
> > with the last patch, OK?  Maybe some of us (e.g., me) don't really
> > understand what is the change.
> 
> It simply makes selecting a region by double-clicking with the mouse
> more uniform; as I wrote in my OP, the current behavior is this:
> 
>    When you select a region by double-clicking with mouse-1 and the end
>    of the region is below the last visible line of the window, Emacs
>    recenters the display, making the entire selected region visible
>    (unless it's larger than half the window's height).  But when you
>    select a region by double-clicking with mouse-1 and the beginning of
>    the region is above the first visible line of the window, Emacs does
>    not recenter the display, so the entire selected region is not
>    visible.
> 
> With the patch the behavior is now simply this:
> 
>    When you select a region by double-clicking with mouse-1, Emacs
>    recenters the display, making the entire selected region visible
>    (unless it's larger than half the window's height).
> 
> To me (and I think Noam agrees), this is the behavior I would expect,
> while the current behavior is less user-friendly; I can't think of a
> reason why anyone would dislike the new behavior or prefer the current
> behavior, but maybe someone can provide a use case.

Thanks, I wanted to be sure I understand the change correctly.

This is indeed a change in behavior: the display recentering in the
second situation might be undesirable, since some text that was
previously visible might become invisible.  And what will happen if
the region is larger than the window can show?

In the first situation, the mouse click actually moves point, so the
scrolling that may follow is expected.  Not so in the second case.

So I still think we should default to the old behavior.