As far as I can work out, this is a good handler to make sure that an About box is shown every time you select Help->About from the menu (i should really look at some other project’s code).

void on_about1_activate(GtkWidget *w)
{
GtkWidget *about;
GladeXML *xml = glade_xml_new (PACKAGE_SOURCE_DIR"/Finance.glade", "about", NULL);
about = glade_xml_get_widget (xml, "about");
gtk_widget_show (about);
gtk_object_unref(GTK_OBJECT(xml));
}