You don't have to prove anything (but informatively, the way to detect wayland session is to check for XDG_SESSION_TYPE env variable). Also, just for curiosity,

You don't have to prove anything (but informatively, the way to detect wayland session is to check for XDG_SESSION_TYPE env variable). Also, just for curiosity, what GPU are you using? It is quite possible that 18.04 has some bugs. I don't have 18.04 machine with hidpi monitor at hand, so I can't have a look myself, so I chalk it up that there is something weird happening.