I don't know, I would not expect any Linux lock screen to be secure secure. More like a padlock to keep honest people honest. If somebody is "good with computer

I don't know, I would not expect any Linux lock screen to be secure secure. More like a padlock to keep honest people honest. If somebody is "good with computers" the'll probably be able to break it. There has been discussion of actually locking the PC when the lock screen is enabled. When you use full disc encryption, it would evict the key from memory when the lock screen goes up. Then, with your password it will unlock the disc and the screen. For this, you'd need to move the login manager to the unencrypted partition and tie the user accounts to the hard disc encryption - I think Windows' BitLocker already does that. In the Linux world, you encrypt the disc before much of the OS loads (from a framebuffer or command line prompt).