On Wednesday 08 February 2017 12.43:43 Dr. Nikolaus Klepp wrote:
> This will most likely not solve your problem for GTK3 applications, but you
> can try to fix the screens DPI:
>
> kcontrol / Apperreance / Fonts : Force DPI ... 96 DPI
>
> For GNOME/GTK please look here: https://wiki.archlinux.org/index.php/HiDPI
>
>
> Nik

Thanks Nik, it did solve the problem, at least for the apps I use on that 
machine (kmail, Vivaldi, Yast). I had never noticed (nor needed) that 
setting, now I know where to look.

Thierry