I recently realized slick-greeter was no more used, since "Arctica Greeter" was used instead. So I adopted the procedure pointed here: https://ubuntu-mate.community/t/how-to-change-lockscreen-and-login-wallpaper-with-arctica-greeter/24242/2 . So I could finally see the background I previously set in vain with "lightdm-settings". I cannot tell why the background in the password input boxes is white, though.
I recently realized slick-greeter was no more used, since "Arctica Greeter" was used instead. So I adopted the procedure pointed here: https:/ /ubuntu- mate.community/ t/how-to- change- lockscreen- and-login- wallpaper- with-arctica- greeter/ 24242/2 . So I could finally see the background I previously set in vain with "lightdm-settings". I cannot tell why the background in the password input boxes is white, though.