sub navbar_callback {
    my ($self, $ht_params, $tmpl_params, $tmpl_file) = @_;

    if( $tmpl_file eq 'master.tmpl' )
    {
        # load your variables
        my %navbar_params = $self->navbar_params;
        $tmpl_params->{$_} = $navbar_params{$_} foreach keys %navbar_params;

        # alternatively, you could also load a separate template for the navbar, and
        # pass it on to the master as a tmpl_var. Note that the if() clause protects you
        # from an infinite loop
        # $tmpl_params->{navbar} = $self->navbar_template;
    }
}

##</code><code>##

sub setup {
    my $self = shift;
    $self->add_callback( 'load_tmpl' => 'navbar_callback' );
}

##</code><code>##

sub cgiapp_postrun {
    my ( $self, $outputref ) = @_;

    # the following conditionals protect us from trampling on
    # 'redirect' runmodes, or non-html output.
    if( $self->header_type eq 'header' ) {
        my %props = $self->header_props;
        if( !exists( $props{'-type'} ) or $props{'-type'} eq 'text/html' ) {

            my $t = $self->load_tmpl('master.tmpl');

            $t->param( runmode_content => $$outputref );
            $t->param( navbar_content  => $self->navbar_template );

            $$outputref = $t->output;

        }
    }
}