Comment 62 for bug 49579

Killing the whole login is pointless because you'd be killing that which a locked screen is meant to protect.
Killing just the X session (client) holding the lock is unacceptable because killing a user's apps or shell is worse than the bug itself.

If we can get the screensaver to just XUngrabKeyboard and XUngrabPointer before it attempts to grab them itself, then that would be great. I'm just not sure if X lets you ungrab grabs you didn't create, so it may not work.