Simple Zenity slider to change current window transparency. Needs a better way to find the Window who called the script. Made for pekwm. Requires: transset-df, zenity and xprop. Rev 3: Now honors Zenity's return value

opacity_zenity.py

#!/usr/bin/python2

import sys, subprocess, os
from subprocess import PIPE, Popen
from threading  import Thread
from Queue import Queue, Empty

def enqueue_output(out, queue):
	for line in iter(out.readline, b''):
		queue.put(line)
	out.close()
#log_file = open(os.path.expanduser("~/opacity_zenity.log"),"a+")

def popen_stdout(args):
	p = subprocess.Popen(args, stdout=subprocess.PIPE)
	return p.communicate()[0]

def transset_df_set_opacity(opval):
	float_val = str(float(opval)/100)
	subprocess.call(["transset-df", "-i", targ_win, float_val])

targ_win = str.split(popen_stdout(["xprop","-root","_NET_ACTIVE_WINDOW"])," ")[4].strip(' \t\n\r')

#log_file.write("""Window is "%s".\n"""%targ_win)

cur_opacity = popen_stdout(["xprop","-id",targ_win,"_NET_WM_WINDOW_OPACITY"])

val = str.split(cur_opacity," ")[2]

if val != "not":
	cur_op = str(int(100*float(str.split(cur_opacity," ")[2].strip(' \t\n\r'))/0xFFFFFFFF))
else:
	cur_op = "100"

#log_file.write("""Current opacity is "%s".\n"""%cur_op)

p = Popen(["zenity","--scale","--print-partial", "--value=%s"%cur_op], stdout=PIPE, bufsize=1, close_fds=True)
q = Queue()
t = Thread(target=enqueue_output, args=(p.stdout, q))
t.daemon = True
t.start()

#log_file.write("Zenity running")

while True:
	try: line = q.get_nowait()
	except Empty:
	    if not t.is_alive():
	    	p.wait()
	    	if p.returncode == 1:
	    		transset_df_set_opacity(cur_op)
	    	break
	else:
		transset_df_set_opacity(line)
		#log_file.write("Opacity set to %s\n"%float_val)
    
#log_file.close()