Improve showed message signal

[Nacho <nacho resa gmail com>]

Hi,

  We have to improve that signal. At the moment the signal is like:

void (*showed_message) (GtranslatorTab *tab,
                                      gpointer data);

and i want something like:

void (*showed_message) (GtranslatorTab *tab,
                                      GList *message,
                                      gpointer data);

Can anybody do that?