With all the studies coming out deploring blue light from screens and TV at night and how absolutely destructive this is to our lives, I was wondering if KDE can implement something around this... Not just a 'blue filter' but an actual theme change.

Vivaldi has a rudimentary theme changer, but it's superficial. What I'd like to see is a schedule based complete theme change including web page inversion, and KDE theme change to night themes.

Currently, I go through a manual routine each day to change to a bright KDE theme for work, and back to a dark theme at night...

It would be nice to automate this.

Open to suggestions Happy to even help develop although I am project manager by trade, not a coder. So I can only help organise things, but not actually code beyond some rudimentary stuff... Happy to learn though.

Imagine a universal theme-switcher API that apps like Vivaldi could hook in to too.... To set a universal 'night schedule'...

It's really total BS that so many modern UI's (namely Windows) and web sites have this obsession with white-washing everything and blinding people at night and ruining their sleep.

Dark text on a white background having a sufficient contrast ratio has been shown to be the most readable, so "white-washing" is actually a good thing, in most circumstances. But like you, at night I prefer a dark theme, so I manually go through the process of changing to a dark look-and-feel. It is VERY easy to do, but it could be made easier by having some sort of look-and-feel widget that allows one to click on it in the panel and select which look-and-feel they want, or have it done automatically at a certain time of day.

I as well would love to see a feature like this. After seeing this post on reddit,
https://www.reddit.com/r/unixporn/comments/5crgng/gnome_when_people_ask_why_i_use_gnulinux/
I was hooked. I find my lovely dark kde setup too dark for daylight work, but the efforts to switch to a brighter lookandfeel currently outweighs the problem. Too much mousing and clicking in systemsettings5. I know from the plasma-sdk package a tool called Plasma Look And Feel Explorer which is aiming to ease the changing of themes, but I cannot get it to work, as all the buttons and such is grayed out and I get the error message 'Impossible to create the layouts directory in the look and feel package' when trying to create a new look and feel scheme.

Just wanted to add my 2 cents of support for this suggestion. I also prefer light themes during the day time, but dark themes in the evening. I use redshift, but even then at night, I find white backgrounds with dark text irritating on the eyes. It would be absolutely wonderful if there was a system wide, one-click or scheduled switch between light and dark themes which also switches applications, especially the web browser.

I was reading this post https://medium.com/elementaryos/the-need-for-a-freedesktop-dark-style-preference-614f501ae4ca, supporting this idea and providing some data, I think is something that can be seen mostly as an accessibility preference. I use redshift also, but this can become a really nice feature.

Curious about this Idea about the blue light as I have bought an eye glass that can filter blue light and it's a bit darker it would be good if it can be done by changing themes not sure what the study on this if this can reduce the blue light? Or even it has a dark theme it still produce a blue light? Though I really this Idea I sometimes use dark theme if my eyes are a bit irritated.

I would absolutely love this feature. For now I will try to automate this via cron:

You can actually control the themes by the commands from command line:
https://userbase.kde.org/KDE_Connect/Tu ... k_and_feel

For instance his will change your theme to breeze dark:

Code: Select all

lookandfeeltool -a 'org.kde.breezedark.desktop'

I added these two lines to crontab:

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0 21 * * * lookandfeeltool -a 'org.kde.breezedark.desktop'
0 7 * * * lookandfeeltool -a 'org.kde.oxygen'


This should change my theme to oxygen at 7am and then to breeze dark at 9 pm (21 hours).

I needed to install cronie (arch linux) for the cron to work as it was not installed by default and also enable cronie service to make cron run automatically:

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systemctl enable cronie.service

hope this helps for now