Newbie question. I need help.

[Javi Roman <javi hardlogic es>]

I have a GnomeUIInfo structure:


static GnomeUIInfo toolbar [] = {
  GNOMEUIINFO_ITEM_STOCK (N_("Admin"), N_("Admin tip"),
                          admini_toolbar_button, "./admin.xpm"),
  GNOMEUIINFO_SEPARATOR,
  GNOMEUIINFO_ITEM_STOCK (N_("Inst"), N_("Inst tip"),
                          inst_toolbar_button, "./inst.xpm"),
 GNOMEUIINFO_END
};



Well, I need pass a argument to "admin_toolbar_button" and
"inst_toolbar_button",
but I don't know.


In GnomeHello example we can see:


static GnomeUIInfo toolbar [] = {
  GNOMEUIINFO_ITEM_STOCK (N_("New"), N_("Create a new hello"),
nothing_cb,  GNOME_STOCK_PIXMAP_NEW),

  GNOMEUIINFO_SEPARATOR,

  GNOMEUIINFO_ITEM_STOCK (N_("Prev"), N_("Previous hello"),
nothing_cb,  GNOME_STOCK_PIXMAP_BACK),

  GNOMEUIINFO_ITEM_STOCK (N_("Next"), N_("Next hello"),
nothing_cb, GNOME_STOCK_PIXMAP_FORWARD),

  GNOMEUIINFO_END
};


......

static void 
nothing_cb(GtkWidget* widget, gpointer data)
{
  GtkWidget* dialog;
  GtkWidget* app;
  
  app = (GtkWidget*) data;

  dialog = gnome_ok_dialog_parented(
          _("This does nothing; it is only a demonstration."),
          GTK_WINDOW(app));
}


Well, "widget" and "data" arguments where are they from?. The caller in
GnomeUIInfo don't have any arguments. I think that I don't understand
very well this concept.


Thanks.