Long notifications would not appear with the default limits.
As cow-notify has no special requirements for a mainloop we can avoid doing sleep cycles. This is not only saving a few cpu cycles, but gives us also 'instant' notifications instead of ~1 sec delays. . The code also passes the used DBusConnection around instead of storing it in a global variable - that's again more a taste than a really needed change.
dbus_message_iter_open_container expects for arrays now that the type of the included elements is provided. Further more doesn't accept _append_fixed_array strings anymore as they are not fixed types, so we add them manually as basic's.
Also try $HOME before pw_dir
Avoid printing useless stuff when not debugging
It does not really change anything, but the code is c99 anyways so..