Suggestion: Blank screen immediately when screen lock is activated

I have been using Ubuntu MATE more recently and I am loving it but I find myself wishing it had one feature which is present in the GNOME release of Ubuntu and serves to make the main Ubuntu release feel like a bit more of a cohesive and well-integrated "product".

I notice that in Ubuntu GNOME when the screen locks through inactivity, or the user locks it with Super+L, the system will also signal the display to enter poweroff/standby immedaitely. I think this is a good approach. In Ubuntu MATE, however, when the system is locked like this then the screen does turn black, but it does not turn off. The display will then stay turned on (just wasting power and displaying only black) until the timeout configured in the "Display" settings of the Power Management tool is reached.

In my case, this means that when I lock my desktop or laptop, the display will remain turned on displaying an empty black screen (but with backlight enabled and using power) for 30 minutes before it eventually turns off.

This is a concern from a power usage perspective if Ubuntu MATE is shooting for power efficiency, as I've heard Martin Wimpress note on the Ubuntu Podcast in the past as being a goal of the project. It's hard to describe but it does also have the effect, as I suggested before, of giving the distro the feeling of a lack of polish when compared to display standby-on-lock being the default behaviour for GNOME, macOS and Win10.

On a less important but related note, it seems like GNOME on a laptop will turn off the keyboard backlight in unison with turning off the display while on Ubuntu MATE the backlight just continues to persist when the device is locked, even once the display has finally powered off.

I don't want this to come across as entirely negative though, as I am a big fan of most of the other design decisions of the flavour. Thanks to all for the great work :slight_smile:


Thanks for the feedback!

If I recall, this is called "screen blanking", and I believe GNOME 2 (before forked as MATE) use to do this too, so it's currently just a continuation of the past. :slight_smile:

Nevertheless, others have raised the issue wish on the MATE project:

Thanks for the pointer! Is this something that's entirely down to the mate-screensaver upstream, or is it something that the Ubuntu MATE team might be engaged with the development of?

Either way, I have bumped the issue on the mate-screensaver issue tracker with a comment.

It would be something for the MATE team to consider, or better yet, someone in the community to propose a patch for. MATE is used across many distros and (we) Ubuntu MATE are just one implementation. Our leader assists with Debian packaging for MATE and MATE developers sometimes drop by our development chat.

The reality is the "Ubuntu MATE Team" is a diverse bunch and there's only @vkareh who really develops across :ubuntu_mate: and :mate: projects.

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For the time being, a fix for this (provided your computer doesn't immediately turn the screen back on) is to invoke DPMS manually after lock using a custom command:

:zzz: Make the display turn off after lock

mate-screensaver-command -la && xset dpms force off

This means also, without editing software for it to knock out the display for you, a custom command always must be used.

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I did an oopsie. Rather than -l by itself, -la should be used instead. By the time you read this I will have applied this correction to the post above.

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It was more complicated than I thought, but if you use the MATE Menu applet in one of your MATE panels then you can follow this guide to make some changes so at least from a GUI you can blank the screen without adding shortcuts to your panels or desktop.


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