Using xfce4-screensaver-0.1.7 (not yet selectable in Bugzilla) I'm experiencing broken screen locking on a laptop that frequently hibernates and wakes up to a different (dual) monitor layout. When this happens: - The primary monitor (on the right) is black, except for the mouse cursor, when it is moved onto it. - there is a hidden password dialog on it. Blindly typing your password into it will unlock and unblank it. - pressing ESC on the primary monitor makes the cursor disappear, presumably together with the hidden password dialog. - The laptop monitor (on the left) is fully exposed. Moving the mouse cursor to it allows interaction with the windows on it, although some things, like dragging windows, will not work. - neither should this monitor be visible, nor should any interaction be possible. I consider this a security breach, breaking the core function of a screensaver/screenlocker. This bug is currently reproducible, in that every wake-up-to-a-different-monitor-layout event makes xfce4-screensaver break in this way. Even restarting the screensaver daemon, then doing another wake-up-to-a-different-monitor-layout event seems to trigger it again. Locking *after* a new monitor layout has been activated doesn't seem to trigger this bug. Clearly xfce4-screensaver has some serious problems with monitor layouts that change while it is blanked/locked. Bug 14782 is probably related.
Created attachment 8845 xfce4-screensaver debug log Attached is a screensaver debug log. At 01:19, the machine was suspended, including screen lock, with the following monitor layout active: 1920x1080 @ 0,0 3440x1440 @ 1920,0 (primary) At 08:44 the following day, it was woken up to this monitor layout, which is automatically activated in the background via a display settings profile: 1920x1080 @ 0,0 3840x1600 @ 1920,0 (primary) The 1920x1080 monitor was completely unobscured and could partially be interacted with via mouse cursor. The 3840x1600 monitor was partially obscured with a 3440x1440-sized black box. No password dialog was shown, the password had to be entered blindly (which makes one wonder wether the passwor dialog even has focus or you're entering your password into the chat program below) From the spam in the log, it seems the screensaver tries to do something repeatedly, but not to much success.
I'm starting to suspect that the screen configuration dialog, which pops up when a new monitor is connected (or when the machine wakes up to a new attached monitor) is responsible for breaking the screensaver. Unfortunately I see no easy way to test this, as having your screens auto-configured invariably includes having the dialog pop up.
I'll close this in favor of bug 14782, which seems to be the go-to bug for "screensaver not locking the right thing/dialog sitting somewhere invisible" issues. *** This bug has been marked as a duplicate of bug 14782 ***