The simple /etc/pm/sleep.d/50_configure-displays script:
----
#!/bin/sh
-
# Configure displays on resume and thaw
case "$1" in
resume|thaw)
- /usr/local/bin/configure_displays
+ if [ -f /usr/local/bin/dispcfg ]; then
+ user=$(ps -fp $((pgrep -x i3 && pgrep -x xfwm4) | tail -1) | awk '{ print $1 }' | tail -1)
+ export DISPLAY=:0
+ export XAUTHORITY=/home/$user/.Xauthority
+ /usr/local/bin/dispcfg
+ fi
;;
esac
----