It does appear to be related to the xrandr scaling experimental feature, after all. Revert that to default and the issue disappears. Guessing that probably makes it a mutter bug, and being of an experimental feature at that is hopefully of interest to someone but not urgent. In view of that didn't test switching pointing device.
** Also affects: mutter (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1829221 Title: second, dead, mouse pointer left on screen after login, x11 session To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-session/+bug/1829221/+subscriptions -- ubuntu-bugs mailing list email@example.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs