WordPressで管理画面に独自に追加したページに表示オプションを追加する

gistfile1.php

<?php
add_action('admin_menu', 'my_plugin_menu');
function my_plugin_menu() {
	global $my_plugin_page;
	$my_plugin_page = add_options_page('My Plugin Options', 'My Plugin', 'Administrator', __FILE__, 'my_plugin_options');
	add_action("load-$my_plugin_page", my_screen_options);
}

function my_screen_options() {
 
	global $my_plugin_page;
 
	$screen = get_current_screen();

	if(!is_object($screen) || $screen->id != $my_plugin_page)
		return;
 
	$args = array(
		'label' => __('Per Page'),
		'default' => 20,
		'option' => 'my_plugin_per_page'
	);
	add_screen_option( 'per_page', $args );
}