// list of QString representations of contact UIDs
// This is already populated for me and I can prove that the 
// strings in it represent valid contact UIDs.
QStringList *selectedContacts = ...;
GtkWidget* contactChooser = osso_abook_contact_chooser_new_with_capabilities (NULL, qPrintable(windowTitle), caps, order);
    osso_abook_contact_chooser_set_minimum_selection(OSSO_ABOOK_CONTACT_CHOOSER(contactChooser), lower_limit);
    osso_abook_contact_chooser_set_maximum_selection(OSSO_ABOOK_CONTACT_CHOOSER(contactChooser), upper_limit);

if (0 != selectedContacts) {
    QString contact;
    foreach (contact, *selectedContacts) {
          OssoABookContact *c = QOssoABookDialog::lookup(contact);
          if (0 != c) {
                g= g_list_prepend(g, c);
          } else qDebug() << "Did not find " << contact;
    }

osso_abook_contact_chooser_select_contacts(OSSO_ABOOK_CONTACT_CHOOSER(contactChooser), g);
}

//Shows a modal dialog.
GList* contacts; // Do not free
if (gtk_dialog_run(GTK_DIALOG(contactChooser)) == GTK_RESPONSE_OK){
  ...
}