$notebook->append_page doesn't return page number :-(

[Dawid Zamirski <dzrudy gmail com>]

Hello

According to the Gtk documentation, the return value of
$notebook->append_page(...); should be an integer that represents the
index of the page that just has been appended (
http://gtk2-perl.sourceforge.net/doc/pod/Gtk2/Notebook.html#integer_notebook_app
). Now I have in my code something like this:

sub onButtonNew_clicked
{
        my $page = $notebook->append_page($gtkwidget1, $gtkwidget2)
        printf($page);
}

.. and I get an error that the argument of printf has undefined
value.. Can someone please explain the proper syntax? Thank You