Fresh installation of Xubuntu 18.04.4, GFX card Nvidia GF119/GT520 - Dual screen setup with 2 very different monitors.
Everything works fine, screen resolution and offset as it should, BUT:
The lock screen looks weird, because it has a quite low and possibly 4:3 resolution (on 16:9 monitors).
When you log back in: Everything's fine.
At least with 1 user.
[SOLUTION]
The workaround mentioned in Launchpad bug #1757202: "nvidia-driver-390 can only be used by one user at a time" seems to work!
I quote it here:
So, here is a workaround for this problem:
1. Create an xorg.conf file for your nVidia device. All you have to do for this is to launch the command:
sudo nvidia-xconfig
This will create a file /etc/X11/xorg.conf.
2. Edit the created file /etc/X11/xorg.conf and add at the end the lines:
Section "Files"
ModulePath "/usr/lib/x86_64-linux-gnu/nvidia/xorg"
ModulePath "/usr/lib/xorg/modules"
EndSection
3. Save and restart the X server. Now, for the first and second user you should have the nvidia driver in use, with the correct resolution and fast rendering. You can check it using the command:
glxgears -info |grep NVIDIA
NOTE: I've used the "nvidia-settings" tool to generate my xorg.conf, because it seemed to fill in my monitor details a bit better than nvidia-xconfig.