i3lock improves slock by making it fork() and therefore combinable with commands
to suspend your computer. Additionally, instead of turning off your screen via
DPMS and/or displaying a black screen, i3lock displays a white screen so you can
see if your computer failed to resume from suspend or if your screen is just
locked. Also, when entering a wrong password, i3lock does not call XBell().
This is important because i3lock/slock think you’ve entered a password when
resuming from suspend, at least sometimes.