Re: Location of mouse click

[Eli Zaretskii <eliz@gnu.org>]

> From: Yasushi SHOJI <yasushi.shoji@gmail.com>
> Date: Fri, 15 Apr 2022 14:11:23 +0900
> Cc: emacs-devel@gnu.org
> 
> On Fri, Apr 15, 2022 at 2:43 AM Eli Zaretskii <eliz@gnu.org> wrote:
> > > > 0. emacs -Q
> > > > 1. open a.txt
> > > > 2. (toggle-truncate-lines)
> > > > 3. goto the end of the last line
> > > > 4. make the frame narrow so that "あ"s are not shown
> > > > 5. click on the last word "dog"
> > > >
> > > > But, this assumes that Japanese and ASCII chars have different heights.
> > > >
> > > > > If it is important to click the mouse at specific
> > > >
> > > > You can click anywhere on the last line.
> > >
> > > Thanks, I see the problem and will look into it.
> >
> > I hope I've now fixed this on the master branch.
> 
> Thank you, Eli.  The change, 67e7870a, works perfectly.

Thanks for testing, and for a clear test case.

> Would you mind backporting to 28? I've tested the change
> by cherry picking on 28, and it works without a glitch.

You are free to use it in your Emacs 28, but I don't consider it safe
enough to have this change in Emacs 28.2 for the general consumption.
As simple and innocent as the change may look, it was done in a very
low-level subroutine, which is used all over the place in display
code.  I cannot predict what issues it could cause elsewhere, which
would require followup changes to unbreak.  OTOH, the problem you
described exists since Emacs 25.1, so it cannot be too annoying, or we
would have heard about it sooner; thus, fixing it is not an urgent
enough need, and doesn't outweigh the potential dangers of
destabilizing the release branch.  Sorry.