the signal identifier, as returned by g_signal_lookup().
the detail on which to call the hook.
a #GSignalEmissionHook function.
user data for @hook_func.
a #GDestroyNotify for @hook_data.
Return: the hook id, for later use with g_signal_remove_emission_hook().
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.