$ xfwm4 --daemon --replace
In the console does not spawn xfwm into the background.
Yeap... Actually, not even w/out --replace.
This is because xfwm4 enters daemon mode only if can't connect to the session manager. Why that, would you ask... Dunno, can't find a reason for that.
Checking history of the file to see...
well, the fix is fairly trivial anyway.