I've noticed in 18.04.2 (upgraded from 16.04 LTS), with gnome-shell 3.28.3-0ubuntu0.18.04.4 and ubuntu-session 3.28.1-0ubuntu3, the *lock* screen is still pinning to /usr/share/gnome-shell/theme/ubuntu.css. Note, the login session screen is using the correct theme.
I also checked the alternative symlinking, and indeed, `pop.css` was supposed to be used, yet the lock screen used ubuntu.css.
```
$ update-alternatives --display gdm3.css
gdm3.css - auto mode
link best version is /usr/share/gnome-shell/theme/pop.css
link currently points to /usr/share/gnome-shell/theme/pop.css
link gdm3.css is /usr/share/gnome-shell/theme/gdm3.css
/usr/share/gnome-shell/theme/pop.css - priority 20
/usr/share/gnome-shell/theme/ubuntu.css - priority 10
```
I've noticed in 18.04.2 (upgraded from 16.04 LTS), with gnome-shell 3.28.3- 0ubuntu0. 18.04.4 and ubuntu-session 3.28.1-0ubuntu3, the *lock* screen is still pinning to /usr/share/ gnome-shell/ theme/ubuntu. css. Note, the login session screen is using the correct theme.
This is related: https:/ /bugs.launchpad .net/ubuntu/ +source/ gnome-shell/ +bug/1732450.
As per https:/ /bugs.launchpad .net/ubuntu/ +source/ gnome-shell/ +bug/1732450/ comments/ 5, the nasty I did to work around it shows the gdm3 / session lock screen theme is still pointed directly to /usr/share/ gnome-shell/ theme/ubuntu. css instead of /usr/share/ gnome-shell/ theme/gdm3. css.
I also checked the alternative symlinking, and indeed, `pop.css` was supposed to be used, yet the lock screen used ubuntu.css.
``` gnome-shell/ theme/pop. css gnome-shell/ theme/pop. css gnome-shell/ theme/gdm3. css gnome-shell/ theme/pop. css - priority 20 gnome-shell/ theme/ubuntu. css - priority 10
$ update-alternatives --display gdm3.css
gdm3.css - auto mode
link best version is /usr/share/
link currently points to /usr/share/
link gdm3.css is /usr/share/
/usr/share/
/usr/share/
```