xfce4-screensaver is invisible when it was invoked by lid closing

[tim474]

When I close my laptop's lid, the xfce4-screensaver lock screen is invisible. I can see my desktop, move mouse cursor, but can't click and type. But if I type the password, the desktop continues to work properly.

I can't see this problem when screensaver was invoked another way: manually (ctrl+alt+L), after suspend, or by timer. In these cases I see the lock screen and the password form

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-screensaver (not installed)
ProcVersionSignature: Ubuntu 5.4.0-33.37-generic 5.4.34
Uname: Linux 5.4.0-33-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.2
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Sat May 30 08:38:27 2020
InstallationDate: Installed on 2020-05-28 (1 days ago)
InstallationMedia: Xubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: gnome-screensaver
Symptom: security
Title: Screen locking issue
UpgradeStatus: No upgrade log present (probably fresh install)

[tim474 (tim474)]

Wrong package name

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Filipe R (ptshello)]

I'm able to reproduce this issue on my Desktop computer (running Xubuntu 20.04.1).

My setup has two monitors: one connected by DisplayPort, and another by HDMI. I can only reproduce this if they are not in mirror mode.
One thing to note is that whenever the DisplayPort monitor is turned off or on (or disconnected), the screens are reconfigured.

To reproduce this issue, I lock the screen (through the screensaver or by invoking xflock4), and then turn the DisplayPort monitor off. After the reconfiguration the desktop is visible, although it's not possible to interact with it.

At this point turning the DisplayPort monitor back on triggers another reconfiguration and the lock screen is visible again.
When the desktop is visible through the lock screen it's possible to type the password and unlock the screen.

[David Mack (barid42)]

This issue also affects me, and has been verified (by me) on two different platforms (Clevo N141CU, Star LabTop Mk IV). Running up-to-date Xubuntu 20.04.1.

[Damian Yerrick (tepples)]

I saw this invisible password entry form on Xubuntu 22.10 and continue to see it on 23.04. (ThinkPad T450)