> Uwe Brauer composed on 2017-08-02 08:18 (UTC):


   > If Trinity Control Center's peripherals display size & orientation screen's

It did not but xrandr returned someting.
   > select list of settings for screen doesn't allow other than screen 1, then
   > install arandr from Ubuntu's standard repos and try it.

Thanks for pointing that out, meanwhile I obtained the relevant xrandr
command for my setting.

Uwe Brauer