基于您的评论，mashable。com菜单是您想要的，我假设您希望HTML的结构与之类似（也就是说ul.menu > li > a + ul.submenu + ul.featured-content). 也就是说，这是真正的实现细节，您可以针对您的用例进行优化。

在我进入代码之前，我应该注意到this is partially pseudocode 因为这个答案的一部分与这个问题没有直接的关系，所以我试图让一个已经很长的答案尽可能简洁。

class WPSE177330_Walker extends Walker_Nav_Menu {
    // Don\'t need to modify start_lvl()
    // Don\'t need to modify end_lvl()
    // Don\'t (necessarily) need to modify start_el()

    /**
    * Outputs the closing for the element.
    *
    * @param string $output Passed by reference. Used to append additional content.
    * @param object $item   Page data object. Not used.
    * @param int    $depth  Depth of page. Not Used.
    * @param array  $args   An array of arguments. @see wp_nav_menu()
    */
    public function end_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
        // Setup indent
        $indent = ( $depth ) ? str_repeat( "\\t", $depth ) : \'\';

        // Capture all top level items and append the featured content
        if ( $depth < 1 ) {
            if ( \'taxonomy\' == $item->type ) {
                // Get your top posts in the category using $item info
                // Assemble output
                // Add it to output
                $output .= $indent . $featured_content;
            } else {
                // What to do with top level menu items that aren\'t taxonomies
            }
        } else {
            // What to do if depth is greater than 1
            // Default behavior
            $output .= "</li>\\n";
        }
    }
}

一定要弄得乱七八糟$item 得到你想要的东西。这是$item 从一个名为“Foo”的类别菜单项中，您可以了解要查找什么，以便准确定制所需的一切。

WP_Post Object
(
    [ID] => 7
    [post_author] => 1
    [post_date] => 2015-02-07 15:29:42
    [post_date_gmt] => 2015-02-07 20:29:42
    [post_content] =>
    [post_title] =>
    [post_excerpt] =>
    [post_status] => publish
    [comment_status] => open
    [ping_status] => open
    [post_password] =>
    [post_name] => 7
    [to_ping] =>
    [pinged] =>
    [post_modified] => 2015-02-07 15:29:42
    [post_modified_gmt] => 2015-02-07 20:29:42
    [post_content_filtered] =>
    [post_parent] => 0
    [guid] => http://sandbox.localhost/?p=7
    [menu_order] => 1
    [post_type] => nav_menu_item
    [post_mime_type] =>
    [comment_count] => 0
    [filter] => raw
    [db_id] => 7
    [menu_item_parent] => 0
    [object_id] => 3
    [object] => category
    [type] => taxonomy
    [type_label] => Category
    [url] => http://sandbox.localhost/category/foo/
    [title] => Foo
    [target] =>
    [attr_title] =>
    [description] =>
    [classes] => Array
        (
            [0] =>
            [1] => menu-item
            [2] => menu-item-type-taxonomy
            [3] => menu-item-object-category
        )
    [xfn] =>
    [current] =>
    [current_item_ancestor] =>
    [current_item_parent] =>
)

我写这篇文章是为了避免使用小部件，正如你在评论中所说的那样。我觉得这是一个更干净的实现，因为它允许您只设置一次，而不会让您的小部件与一堆特定于菜单的小部件混在一起。如果您想改用小部件（正如您最初提议的那样），也许为了比硬编码解决方案更灵活一些，您可以为每个顶级菜单项注册小部件，然后使用相同的自定义概念Walker_Nav_Menu 扩展以显示这些小部件。