Comment 8 for bug 1088392

This bug is present in Ubuntu 15.4. I've also experienced identical behavior in Mint.

I have frequently been able to observe information on a monitor or operate the keyboard and mouse within a session for a couple of seconds between when the monitor wakes and when the screen lock intervenes.

What concerns me most about this bug is that it allows an knowledgeable lurker a peek into a system every time it is left unattended, even if the screen turns off due to inactivity.