Raise all windows of the active one. Bind this to a shortcut (such as SUPER + UP) and when you press all windows of this app goes foreground. With a special hack for CSSH. Taken from here with updates: http://askubuntu.com/questions/446521/how-to-show-all-windows-of-an-application/

raise_windows.py

#!/usr/bin/env python3
import subprocess
import getpass
import time

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

def execute(command):
    subprocess.Popen(["/bin/bash", "-c", command])

def get_frontmost():
    cmd = "xprop -root"
    frontmost = [l for l in get(cmd).splitlines() if\
                 "ACTIVE_WINDOW(WINDOW)" in l][0].split()[-1]
    first_part = frontmost[:2]
    last_part = frontmost[2:]
    return first_part + '0' * (8 - len(last_part)) + last_part

def get_full_data(text, w_data):
    for l in w_data:
        if text in l:
            return l.split()
   
# calculate screen resolution
res_output = get("xrandr").split(); idf = res_output.index("current")
res = (int(res_output[idf+1]), int(res_output[idf+3].replace(",", "")))
# get window data for various purposes
w_data = get("wmctrl -lpG").splitlines()
non_windows = sum([[l.split()[0] for l in w_data if it in l]\
               for it in ("unity-launcher", "unity-panel", "unity-dash", "Hud")], [])
# get id of current window
curr_window = get_frontmost()
# user gets 3 seconds to pick an application window (or launcher icon)
t = 0
# while t < 4:
#    w_id1 = get_frontmost()
#    time.sleep(1)
#    w_id2 = get_frontmost()
#    if w_id1 == w_id2 or w_id2 in non_windows+[curr_window]:
#        t = t+1
#    else:
#        new_frontmost = w_id2
#        break

new_frontmost = get_frontmost()
# raise
try: 
    full_data = get_full_data(new_frontmost, w_data)
    if full_data[8] in ['CSSH', 'CSSH:']:
         pids = [l.split()[2] for l in w_data if 'CSSH' in l.split()[8] in ['CSSH', 'CSSH:']]
    else:      
        group = full_data[5]
        pids = [l.split()[2] for l in w_data if l.split()[5] == group]
    
    wl_data = [l.split() for l in w_data]
    raise_windows = [l[0] for l in wl_data if l[2] in pids and\
                     0 < int(l[3]) < res[0] and 0 < int(l[4]) < res[1]]
    [execute("wmctrl -ia "+item) for item in raise_windows]
except NameError:
    pass