Change the lock screen program

The X11 session (i3) and the Wayland session (sway) lock the screen with different programs, so they are configured separately.

X11 session

Configure gnome-flashback to Disable Built-in Lockscreen

By default gnome-flashback handles the lock screen in the X11 session. This can be adjusted by modifying its configuration via the gsettings command line program:

gsettings set org.gnome.gnome-flashback screensaver false

gnome-flashback also locks the screen when the session is idle and before the computer suspends. With its lock screen disabled, these locks no longer happen; set them up yourself if you need them (for example with xss-lock).

Cause Your Lock screen program to Run from i3 Keybinding

Specify the following override line in your ~/.config/regolith3/Xresources file (substituting your-script.sh with the command you wish to use for the locking your screen):

wm.program.lock_i3: your-script.sh

For example, assuming you have i3lock installed:

echo "wm.program.lock_i3: /usr/bin/i3lock" >> ~/.config/regolith3/Xresources
regolith-look refresh

The lock screen keybinding, super escape, then runs i3lock.

Wayland session

The Wayland session locks the screen with gtklock. The Xresource wm.program.lock_sway sets the lock command. It is used for the lock screen keybinding, after the session has been idle, before the computer suspends, and when the lid is closed. The command must return once the screen is locked, so start the locker in the background (for example swaylock -f or gtklock -d):

sudo apt install swaylock
echo "wm.program.lock_sway: swaylock -f -c 000000" >> ~/.config/regolith3/Xresources
regolith-look refresh

The gsettings command above has no effect in the Wayland session.