@jamesh your stack trace is caused by Ubuntu Dock's dynamic transparency which I mentioned before in Comment #17 and can be disabled with the following terminal command:
gsettings set org.gnome.shell.extensions.dash-to-dock transparency-mode FIXED -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1769383 Title: Ubuntu dock/launcher is shown on the lock screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1769383/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
