light-locker switches virtual terminals on lock and unlock

[Martin Spacek]

I know this is, strangely, by design (http://xubuntu.org/news/screen-locking-in-xubuntu-14-04/), but compared to gnome-screensaver or xscreensaver, it's a regression as far as I'm concerned. I couldn't find any placeholder bug for this. If there is one already, then please mark this as duplicate, and sorry for the noise.

A summary of what's wrong with switching VTs:

1. Locking takes ~4 seconds in Xubuntu 14.04 on my Thinkpad W510 with nvidia binaries installed. Unlocking takes another ~4 seconds. That's a total of 8 seconds for a lock/unlock cycle, not including password entry. That's simply terrible terrible usability. Locking and unlocking were basically instant in both gnome-screensaver and xscreensaver.

2. Locking and unlocking both result in some serious screen flashing, plus in my case, the brief display of the nvidia logo. This gives the very strong impression that X has just crashed and restarted. That was my conclusion the first few times it happened. All this VT switching can't be great for the hardware either, especially the backlight.

3. Audio playback stops on VT switch. A lot of us leave our laptops playing music on external speakers while we're in the next room doing something else for who knows how long. Having it stop just because the screensaver has been triggered is another usability fail.

I suppose VT switching is being used for some kind of security guarantee (is there a reference for that somewhere?). However, IMO, using VT switching for locking and unlocking is a major fundamental design flaw, resulting in serious usability issues. As a result, light-locker is far from ready for prime time. Rolling it out for an LTS was a big mistake.

[Simon Steinbeiß (ochosi)]

Yup, this is by design, but not by light-locker per se, but LightDM. We have locking without VT switching on our roadmap, but as both of us main developers are busy right now, I don't see it happening very soon.

As you said, there are other screensavers that don't do VT switches. Use one of those.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ian Phillips (ianfp)]

For other users affected by this, this link has more info and workaround instructions:

http://askubuntu.com/questions/450443/light-locker-stops-background-activities-eg-music-playback-when-screen-is-loc