Screensaver

Replace xscreensaver with i3lock

XFCE4 uses /usr/bin/xflock4 to select the screensaver. Uninstall xscreensaver so we can override it.

# Remove xscreensaver
sudo dpkg -r --force-depends xscreensaver

Create /usr/bin/xscreensaver-command. Prevent a user running it more than once:

#!/bin/sh
LOCKER=i3lock
ARGS="-c 103010"

if ! pgrep -u $USER "$LOCKER|$0"
then
    $LOCKER $ARGS
fi