Ok, my guess was not true. It’s the new wp_enqueue_script handling in WP 2.8 (beta2) that breaks the plugin.
I’ve fixed it as follows:
function mypageorder_js() {
if ( $_GET['page'] == "mypageorder" ) {
echo "<script type='text/javascript' src='https://example.org/wordpress/wp-admin/load-scripts.php?c=1&load=hoverIntent,common,jquery-color,jquery-ui-core,jquery-ui-sortable&ver=68c730824fe93e0fc4dc0373bd1d3632'></script>";
}
}
add_action('admin_menu', 'mypageorder_menu');
//add_action('admin_menu', 'mypageorder_js_libs');
add_action('admin_head', 'mypageorder_js');