Adds an emission hook for a signal, which will get called for any emission of that signal, independent of the instance.
This is possible only for signals which don't have g_signal_no_hooks flag set.
the signal identifier, as returned by lookup.
the detail on which to call the hook.
a SignalEmissionHook function.
a DestroyNotify for
user data for
the hook id, for later use with remove_emission_hook .