Aero snap effect linux metacity multiple screens

aero.py

#!/usr/bin/env python3
# From Jacob Vlijm posted in askubuntu.com

import subprocess
import sys

move = sys.argv[1]

def get(cmd):
    return subprocess.check_output(["/bin/bash", "-c", cmd]).decode("utf-8")
def execute(cmd):
    subprocess.call(["/bin/bash", "-c", cmd])

# screen resolutions ("raw")  
wds = [s for s in get("xrandr").split() if s.endswith("+0")]
# x-res left/right)
left = [scr.split("x")[0] for scr in wds if scr.endswith("+0+0")]
right = [scr.split("x")[0] for scr in wds if not scr.endswith("+0+0")]
# x-positions areas
left_pos = [0, int(int(left[0])/2), int(left[0])]
right_pos = [int(int(left[0])+int(right[0])/2)] if len(right) != 0 else []
x_positions = left_pos+right_pos
# frontmost window pos
frontmost = [l.split()[-1] for l in get("xprop -root").splitlines() if "ACTIVE_WINDOW(WINDOW)" in l][0]
frontmost = frontmost[:2]+"0"+frontmost[2:]
print(get("wmctrl -lG"))
# FIXME - the line below fails when executed on a gnome-terminal 14.10 metacity
f_data = [l.split() for l in get("wmctrl -lG").splitlines() if frontmost in l][0][:6]
curr_pos = int(f_data[2])
area = len([x for x in x_positions if x <= curr_pos])
if move == "left":
    i = area-2; target_pos = x_positions[i] if i >= 0 else 0 
elif move == "right":
    i = area; target_pos = x_positions[area] if area < len(x_positions) else x_positions[-1]
if i >= 2:
    perc = int((100*(x_positions[-1]-x_positions[-2])/sum([int(it) for it in left+right])))
else:
    perc = int((100*(x_positions[1]-x_positions[0])/sum([int(it) for it in left+right])))
# execute actions
cmd1 = "wmctrl -r :ACTIVE: -b remove,maximized_vert,maximized_horz"
cmd2 = "wmctrl -ir "+f_data[0]+" -e 0,"+str(target_pos)+","+"30,300,300"
cmd3 = "xdotool windowsize $(xdotool getactivewindow) "+str(perc)+"% 100%"
for cmd in [cmd1, cmd2, cmd3]:
    execute(cmd)

On AU, updated my answer. replaced the command to find frontmost window, which seems to cause the problem. http://askubuntu.com/a/572052/72216