18408-test-metabox.php

<?php
/**
 * Plugin Name: 18408 test metabox
 * Plugin URI: https://core.trac.wordpress.org/ticket/18408
 */
add_action( 'add_meta_boxes', 'myplugin_add_custom_box' );

function myplugin_add_custom_box() {
	add_meta_box(
		'myplugin_sectionid',
		__( 'My Post Section Title', 'myplugin_textdomain' ),
		'myplugin_inner_custom_box',
		'post',
		'side'
	);
}

function myplugin_inner_custom_box() {
	global $post;
	$a = new WP_Query('post_type=page');
	while($a->have_posts() ) : $a->the_post();
	endwhile;
	wp_reset_postdata();
	the_title();
}