Thanks, I found this page which outlines the fallback process a little better. https://www.nkuttler.de/2010/06/08/wp_nav_menu-wordpress-3-0/
For anyone else with this same dilemma, I’ve posted my code for reference:
header.php:
<!-- begin navigation -->
<div id="navwrap">
<div id="nav">
<?php st_navbar(); ?>
</div><!--/nav-->
</div>
<!--/end navigation-->
functions.php:
(sthemes_topmenupages and sthemes_topmenucats assumes a fallback theme admin panel option is also used to output comma separated values)
// WP 3.0 Menus
function mytheme_addmenus() {
register_nav_menu('top-menu', 'Primary Navigation');
}
add_action( 'init', 'mytheme_addmenus' );
function st_navbar() {
if (function_exists('wp_nav_menu' ))
wp_nav_menu( 'menu=top-menu&depth=2&menu_class=sf-menu sf-navbar&fallback_cb=st_navbar_fallback' );
else
st_navbar_fallback();
}
function st_navbar_fallback() {
$topmenupages = array(
'include' => get_option('sthemes_topmenupages'),
'depth' => 3,
'sort_column' => menu_order,
'hierarchical' => true,
'title_li' => __('')
);
$topmenucats = array(
'include' => get_option('sthemes_topmenucats'),
'depth' => 2,
'title_li' => __('')
);
echo "<ul class=\"sf-menu sf-navbar\">";?>
<li <?php if ( is_home() ) { ?>class="current_page_item"<?php } ?>>
<a href="<?php echo get_option('home'); ?>/"><?php _e ('Home', 'smpl') ?></a>
</li>
<?php
wp_list_pages($topmenupages);
wp_list_categories($topmenucats);
echo "</ul></div></div>";