More investigation shows that this is actually a Unity bug. The black screen you are seeing is the lock screen but Unity doesn't have a lock screen when in guest mode. The lock screen is triggered when you switch users via the indicator.
You can also trigger this by typing alt+ctrl+L inside the guest session. It will show a black screen that disappears when you move the mouse. The solution should be that Unity does nothing when the lock screen is requested to be activated. ** No longer affects: lightdm ** Package changed: lightdm (Ubuntu) => unity (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1405349 Title: switching to activated guest session causes screen blank To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/1405349/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
