Add metabox to WordPress menu editor

obi-nav-metabox.php

<?php
//add_action( 'admin_init', 'obi_add_meta_box' );

// load-nav-menus.php is the perfect hook for this metabox
// as we are only adding on nav menu page :)
add_action( 'load-nav-menus.php', 'obi_add_meta_box' );

function obi_add_meta_box() {
	add_meta_box(
		'obi-nav-metabox',
		__( 'One Page Navigation', 'obi' ),
		'obi_render_nav_metabox',
		'nav-menus',
		'side',
		'core'
		);
}

function obi_render_nav_metabox() {
	echo '<strong>Hello World, This is Obi Plabon</strong>';
}