I downloaded latest wordpress yeaterday. The menu in admin panel are now arranged horizontally and it's difficult to arrange with sub menus.
I created custom theme then found no menu option under the APPEARENCE. So I added the below code in functions.php
//add menu option in the admin panel sidebar APPEARENCE
function wpb_custom_new_menu() {
register_nav_menu('main-navigation',__( 'Main Navigation' ));
}
add_action( 'init', 'wpb_custom_new_menu' );
Now the menu option added, but it looks weird as attached.

Is there any way to arrange it back to vertical?