Apple Script to prevent firefox from running while it is without focus

PauseFirefoxSwitchWithPid.applescript

# Reference http://stackoverflow.com/questions/7741879/if-i-wanted-to-modify-task-switching-in-osx
# Reference http://apple.stackexchange.com/questions/36163/applescript-kill-command-error
# http://lists.apple.com/archives/applescript-users/2012/Nov/msg00070.html
# SIGCONT and SIGSTOP don't work in shell executed by applescript.
# Has to use numbers, or STOP/CONT w/o SIG or use "set +o posix"
# http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7
# http://superuser.com/questions/14762/execute-applescript-without-open-the-editor
# http://stackoverflow.com/questions/13653358/how-to-log-objects-to-a-console-with-applescript
# http://lists.apple.com/archives/applescript-users/2013/Apr/msg00024.html
# http://en.wikipedia.org/wiki/AppleScript -- for on quit handler
# For path to frontmost application: http://apple.stackexchange.com/a/145090
#
# #
#

#on main
set app_name to "Firefox"

# Added this new var because I'm using FirefoxDevelop edition too
set app_name_with_app to "Firefox.app"
set the_pid to (do shell script "ps ax | grep " & (quoted form of app_name_with_app) & " | grep -v grep | grep -v CrashReporter | grep -v applescript | awk '{print $1}'")

set app_stopped to false

log the_pid

repeat
	tell application "System Events"
		set a to first process whose frontmost is true
        set frontApp to (path to frontmost application as Unicode text)
		if name of a is equal to app_name and frontApp ends with "Firefox.app:" then
			if the_pid is not "" and app_stopped is true then 
                do shell script ("kill -CONT " & the_pid)
                set app_stopped to false
                #log "app continued"
            end if
		else
			if the_pid is not "" and app_stopped is false then 
                do shell script ("kill -STOP " & the_pid)
                set app_stopped to true
                log "app stopped"
            end if
		end if
	end tell
	
    #do shell script ("sleep 1")
    delay 1
end repeat

#end main