Emits a signal.
Signal emission is done synchronously. The method will only return control after all handlers are called or signal emission was stopped.
Note that emit resets the return value to the default if no handlers are connected, in contrast to
the instance the signal is being emitted on.
the signal id
parameters to be passed to the signal, followed by a location for the return value. If the return type of the signal is g_type_none, the return value location can be omitted.