bug#44284: 27.1; with some Unicode font, scrolling upward with the mouse wheel actually scrolls downward when the cursor needs repositioning

[Eli Zaretskii]

> Date: Fri, 30 Oct 2020 14:33:36 +0100
> From: Vincent Lefevre <vincent@vinc17.net>
> Cc: 44284@debbugs.gnu.org
> 
> On 2020-10-30 13:31:54 +0200, Eli Zaretskii wrote:
> > Thanks.  This means that I will need a reproduction recipe with some
> > less Unix-specific font, because I tried a lot of different font sizes
> > and couldn't reproduce the problem, at least not in "emacs -Q".
> 
> Note that here the bug is reproducible with
> 
>   -misc-fixed-bold-r-normal--13-100-100-100-c-70-iso8859-1
>   -misc-fixed-bold-r-normal--13-100-100-100-c-80-iso8859-1
>   -misc-fixed-medium-r-normal--13-100-100-100-c-70-iso8859-1
>   -misc-fixed-medium-r-normal--13-100-100-100-c-80-iso8859-1
>   -misc-fixed-medium-r-normal--13-120-75-75-c-70-iso10646-1
>   -misc-fixed-medium-r-normal--13-120-75-75-c-80-iso10646-1
>   -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso10646-1
> 
> but not with
> 
>   -misc-fixed-medium-r-normal--0-0-75-75-c-0-iso10646-1
>   -misc-fixed-medium-r-normal--8-80-75-75-c-50-iso10646-1
>   -misc-fixed-medium-r-normal--9-90-75-75-c-60-iso10646-1
>   -misc-fixed-medium-r-normal--10-100-75-75-c-60-iso10646-1
>   -misc-fixed-medium-r-normal--14-130-75-75-c-70-iso10646-1
>   -misc-fixed-medium-r-normal--15-140-75-75-c-90-iso10646-1
>   -misc-fixed-medium-r-semicondensed--0-0-75-75-c-0-iso10646-1
>   -schumacher-clean-medium-r-normal--12-120-75-75-c-60-iso10646-1
> 
> So it seems to be the "13" that is the problem.

Yes, but I don't have access to a system with misc-fixed font, and the
replacement I have here refuses to reproduce the problem with many
sizes I tried.  So I need help in reproducing the issue, before I
could debug it.

Thanks.