bug#50256: thing-at-mouse

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Wed, 01 Sep 2021 18:42:35 +0300
> Cc: 50256@debbugs.gnu.org, Lars Ingebrigtsen <larsi@gnus.org>
> 
> >>    if (EQ (pos, Qt))
> >>      posint = -1;
> >>    else if (!NILP (pos))
> >>      posint = fix_position (pos);
> >>    else if (w == XWINDOW (selected_window))
> >>      posint = PT;
> >>    else
> >>      posint = marker_position (w->pointm);
> >
> > Using the position of point of the current buffer when WINDOW is
> > specified doesn't make any sense.  Moreover the Elisp manual says that
> >
> >   "The argument POSITION defaults to the current position of point in
> >   WINDOW"
> >
> > which doesn't make sense if point is taken from a buffer not shown in
> > WINDOW.  So the fix should be implemented in Fpos_visible_in_window_p.
> 
> Actually, WINDOW is not specified, but defaults to the selected window.
> But still you point is valid: using the position of point of the current 
> buffer
> for the selected window doesn't make sense.

It makes perfect sense, because this code cannot work if the current
buffer and the selected window's buffer are different.