The lock screen (when you are away from your computer activated with Super +k) is provided by the application xfce-slimlock and slim.
We have provided already 5 ArchLabs screenlock choices. They can be found in /usr/share/slim/themes.
While writing this article I created archlabs_transfer (4k – 3840×2160 – wallpaper) (created after release of R2-D2)
More will surely follow. These themes are updated with packer and the package is called archlabs-slimlock-themes-git.
However the configuration file is in /etc/slim.conf. You will need to edit this file to add new themes or delete themes you do not like.
You can get at this file via your menu.
To have archlabs_transfer you will have to edit the /etc/slim.conf and add a line for any new theme like
#current_theme archlabs, archlabs_nature, archlabs_wood , archlabs_neutral, archlabs_black_spots, archlabs_transfer