Changes XFCE panel transparency depending on whether any window on the current workspace is maximized or not #script

xfce4-panel-auto-opaque.sh

#!/usr/bin/env bash

#-- CONFIGURATION
transparent_alpha=0
maximized_alpha=100
interval=0.5
#--

alpha_prop_list=()
for prop in $(xfconf-query -c xfce4-panel -p /panels -l); do
	[[ "$prop" == *"background-alpha"* ]] && alpha_prop_list+=($prop)
done

on_maximized() {
	for alpha_prop in "${alpha_prop_list[@]}"; do
		xfconf-query -c xfce4-panel -p "$alpha_prop" -s "$maximized_alpha"
	done
}

on_no_window_maximized() {
	for alpha_prop in "${alpha_prop_list[@]}"; do
		xfconf-query -c xfce4-panel -p "$alpha_prop" -s "$transparent_alpha"
	done
}

echo $alpha_prop_list

while true; do
	current_desktop=$(wmctrl -d | grep '*' | cut -d ' ' -f1)
	is_any_window_maximized=false
	for i in $(wmctrl -lG | awk -v d="$current_desktop" '$2==d {print $1}'); do
		status=$(xprop -id $i _NET_WM_STATE)
		if [[ "$status" == *"MAXIMIZED"* && "$status" != *"HIDDEN"* ]]; then
			is_any_window_maximized=true
			break
		else
			is_any_window_maximized=false
		fi
	done
		
	if [[ $is_any_window_maximized == true ]]; then
		on_maximized
	else
		on_no_window_maximized
	fi
	
	sleep $interval
done

This is great! Does either of these versions work for the 4.12 as well?

Yes - tested and fully working with 4.12 as well. To make sure, I added a condition to check the installed xfce4-panel version (line 33).

Good job. Add bc in "Required software" list. And have you any idea how to fix color changing lag? It does not occur when you open panel preferences and there change panel color, in this time rectangle around panel flashes, may be it is reason that avoids lag? What do you think about it?

Good catch! Added bc to the requirements. On Arch Linux, it already came installed as a dependency from cups. Not sure on Ubuntu.

Yeah, I think you're on to something as well regarding the refresh issue; the delay is almost unnoticeable from the panel settings. Maybe it enforces refreshing when the user changes values? The enter/leave opacity values for the panel are also refreshed instantly when applied.

And if you monitor panel with: xfconf-query -c xfce4-panel -m -v and change color from panel preferences you'll see that it changes just background-rgba property to ((null)) and there's also warning: "Unable to convert GValue to string".
Seems like bug ?

Looking further, I found the line which issues the error message in xfconf source code (here). However, it only seems to output the error message when in verbose mode (-v); otherwise, it just prints the panel name i.e. set: /panels/panel-X/background-rgba when changed.

I also narrowed down the moment it issues the error (here). It might be because GValue in this case is an array with 4 values (rgba)?