As discussed here: https://forum.antergos.com
Gnome seems to overwrite the settings to black the screen for powersaving, made by other DM's then GDM, as allways under Gnome: Devs there do not take care to make it easy to customize.
We find out some solutions to solve this, and get lightlocker work under Antergos Gnome, as we do not use GDM by default, we get Lightdm and lightlocker instead!
Here the best working solution (IMHO):
Disable gsd-power plugin
Completely disable gsd-power plugin by patching the desktop file:
echo "Hidden=true" | sudo tee -a /etc/xdg/autostart/org.gnome.SettingsDaemon.Power.desktop
and restart session.
If you want the changes to become permanent so that the file cannot be modified with updates, then you can use the 'chattr' command (you can always roll back the changes below with the "-i" parameter):
sudo chattr +i /etc/xdg/autostart/org.gnome.SettingsDaemon.Power.desktop
Another way is to do this if you prefer not to interfere with global files that may be subject to update changes, you can enable the changes on a per-user basis by copying the file to the
directory in your home dir and then add the key by doing
cp /etc/xdg/autostart/org.gnome.SettingsDaemon.Power.desktop ~/.config/autostart/ echo "Hidden=true" >> ~.config/autostart/org.gnome.SettingsDaemon.Power.desktop
As provided here by shane
Now you can use lightlocker:
All setting related to screen-locking and poweroff screen from gnome-settings should be disabled: