lockscreen allows ~0.5s of visibility of previous unlocked screen content

I'm not sure what package provides the lockscreen on 15.10.

This seems to happen only when the screen is unlocked, and the laptop lid is closed. Upon awakening, the screen is unlocked for about half a second. I don't know if any interaction is possible during that time, but even displaying the unlocked screen contents is already problematic.

I believe this is a recent regression.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: gnome-screensaver 3.6.1-7ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3
Uname: Linux 4.2.0-18-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Nov 28 21:39:22 2015
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GsettingsGnomeSession:
 org.gnome.desktop.session session-name 'ubuntu'
 org.gnome.desktop.session idle-delay uint32 300
InstallationDate: Installed on 2015-11-10 (19 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: gnome-screensaver
UpgradeStatus: No upgrade log present (probably fresh install)