Multi monitor support

When restarting i3 check for connected second monitor: scale it and
restart polybar if there is one.
Put polybar tray on the main monitor.
Do not kill polybar and relaunch it when restarting i3, but restart it
using ipc (much faster).

.config/polybar/config

@@ -24,7 +24,7 @@ modules-left = i3 pulseaudio xbacklight battery-custom
 modules-center = datetime
 modules-right = vpn wlan bluetooth powermenu
 
-tray-position = right
+tray-position = ${env:TRAY_POS:right}
 tray-detached = false
 tray-scale = 1.0
 
@@ -36,10 +36,13 @@ foreground = ${colors.foreground}
 line-size = 3
 line-color = ${colors.primary}
 
+enable-ipc = true
+
 ;#################################################
 
 [module/i3]
 type = internal/i3
+pin-workspaces = true
 format = <label-state> <label-mode>
 index-sort = true
 wrapping-scroll = false

.config/polybar/launch.sh

@@ -3,10 +3,16 @@
 # if there is no running instance
 if ! pgrep -ax polybar >/dev/null 2>&1; then
 	# launch Polybar on every monitor
-	# https://github.com/polybar/polybar/issues/763#issuecomment-392960721
+	# https://github.com/polybar/polybar/issues/763
+	primary="$(xrandr -q | grep primary | cut -d' ' -f1)"
 	for m in $(polybar --list-monitors | cut -d':' -f1); do
-		MONITOR=$m polybar --reload -c "$HOME/.config/polybar/config" main &
+		export TRAY_POS=none
+		[ "$m" != "$primary" ] || export TRAY_POS=right
+		export MONITOR="$m"
+		polybar --reload -c "${XDG_CONFIG_HOME:-$HOME/.config}/polybar/config" main &
 	done
 
 	echo "Polybar launched..."
+else
+	polybar-msg cmd restart
 fi