If the screen was locked while two were monitors connect, the unlock screen does not appear after disconnecting second monitor

Submitted by leo..@..il.com

Assigned to Sean Davis @bluesabre

Link to original bug (#15925)

Description

It was noticed that in certain dual monitor setups, if the screen is locked and the the second monitor is removed with the lock screen active, the unlock screen never appears. What appears in what now is the only monitor is the frozen screensaver. The unlock screen is functional, however it is not visible, so writing the password and pressing Enter works, but this is not an adequate behavior.

The following image shows the dual monitor setup: https://i.imgur.com/F2Cr1rw.png The monitor that can be removed is the LG 19" one.

Bug 14796 sounds similar, but is marked as solved.

OS: Xubuntu 18.04, using Staging PPA GPU: Intel HD Graphics 520, using intel Xorg driver

$ xfce4-screensaver --version xfce4-screensaver 0.1.8