Fetch TinyMCE per AJAX. Media upload doesn’t work yet.

t5-ajax-editor.php

<?php
/**
 * Plugin Name: T5 AJAX Editor
 */

namespace T5AjaxEditor;


class Controller implements Event_Handler
{
	private $editor_id    = 't5_ajax_editor';
	private $ajax_action  = 't5_test_editor';
	private $admin_action = 't5_test_editor';

	private $page_output;
	private $validator;

	public function __construct()
	{
		$data            = new Options_Data( $this->editor_id );
		$this->validator = new Basic_Request_Validator( 't5_ajax_test' );

		if ( $this->is_ajax() )
		{
			$editor = new Ajax_Editor( $data, $this->validator, $this->editor_id );
			add_action( "wp_ajax_$this->ajax_action", [ $editor, 'render' ] );
			return;
		}

		$this->page_output = new Options_Page( $this, $this->admin_action );
		$admin_post = new Admin_Post_Handler( $data, $this->validator, $this->editor_id );
		add_action( 'admin_menu', [ $this, 'register_page' ] );
		add_action( 'admin_post_' . $this->admin_action, [ $admin_post, 'update' ] );
	}

	public function register_page()
	{
		$title = 'AJAX Editor';
		add_menu_page(
			$title,
			$title,
			'manage_options',
			'ajax-test',
			[ $this->page_output, 'render' ]
		);
	}

	public function trigger_event( $name, $data = NULL )
	{
		if ( 'admin.options_page.form.content' === $name )
		{
			$content = new Options_Page_Form_Ajax_Content( $this->validator, $this->ajax_action );
			$content->render( 'get_editor', 't5_editor_container' );
		}
	}

	private function is_ajax()
	{
		return defined( 'DOING_AJAX' ) && DOING_AJAX;
	}
}

class Ajax_Editor
{
	private $data;
	private $validator;
	private $editor_id;
	private $settings = [ 'media_buttons' => FALSE ];

	public function __construct( Data $data, Request_Validator $validator, $editor_id )
	{
		$this->data      = $data;
		$this->validator = $validator;
		$this->editor_id = $editor_id;
	}

	public function render()
	{
		if ( ! $this->validator->is_valid( TRUE ) )
			die( 'nope' );

		wp_editor( $this->data->get(), $this->editor_id, $this->settings );
		\_WP_Editors::enqueue_scripts();
		print_footer_scripts();
		\_WP_Editors::editor_js();

		die();
	}

	public function change_settings( Array $settings )
	{
		$this->settings = $settings;
	}
}

class Options_Page
{
	private $event_handler;
	private $admin_action;

	public function __construct( Event_Handler $event_handler, $admin_action )
	{
		$this->event_handler = $event_handler;
		$this->admin_action  = $admin_action;
	}

	public function render()
	{
		global $title;
		?>
<div class="wrap">
	<h1><?=$title?></h1>
	<form method="post" action="<?php print admin_url( 'admin-post.php' ); ?>">
		<input type="hidden" name="action" value="<?=$this->admin_action?>">
		<?php
		$this->event_handler->trigger_event( 'admin.options_page.form.content' );
		submit_button();
		?>
	</form>
</div>
	<?php
	}
}

class Options_Page_Form_Ajax_Content
{
	private $validator;
	private $ajax_action;

	public function __construct( Request_Validator $validator, $ajax_action )
	{
		$this->validator   = $validator;
		$this->ajax_action = $ajax_action;
	}

	public function render( $button_id, $container_id )
	{
		wp_nonce_field(
			$this->validator->get_nonce_action(),
			$this->validator->get_nonce_name()
		);
		?>
		<div id="<?=$container_id?>">
			<?php
			submit_button( 'Get Editor', 'secondary', $button_id, FALSE );
			?>
		</div>
		<?php
		$this->get_script( $button_id, $container_id );
	}

	private function get_script( $button_id, $container_id )
	{
		$nonce_name = $this->validator->get_nonce_name();
		$nonce_value = wp_create_nonce( $this->validator->get_nonce_action() );
		?>
		<script>
			jQuery(document).ready(function( $ ){
				$('#<?=$button_id?>').click(
					function() {
						var data = {
							<?=$nonce_name?>: '<?=$nonce_value?>',
							action: '<?=$this->ajax_action?>'

						};
						$.post(ajaxurl, data, function( html ) {
							$( "#<?=$container_id?>" ).html( html );
						});
						return false;
					}
				);
			});
		</script>
	<?php
	}
}

interface Event_Handler
{
	public function trigger_event( $name, $data = NULL );
}

interface Request_Validator
{
	public function __construct( $base, $network = TRUE );

	public function get_nonce_name();

	public function get_nonce_action();

	public function is_valid( $ajax = FALSE );
}

class Basic_Request_Validator implements Request_Validator
{
	private $action;
	private $name;

	public function __construct( $base, $network = TRUE )
	{
		$this->name = $base . '_name';
		if ( ! $network )
			$this->name .= '_' . get_current_blog_id();

		$this->action = $base . '_action';
	}

	public function get_nonce_name()
	{
		return $this->name;
	}

	public function get_nonce_action()
	{
		return $this->action;
	}

	public function is_valid( $ajax = FALSE )
	{
		return wp_verify_nonce( $_REQUEST[ $this->name ], $this->action );
	}
}

interface Data
{
	public function get();
	public function save( $value );
}

class Options_Data implements Data
{
	private $name;

	public function __construct( $name )
	{
		$this->name = $name;
	}

	public function get()
	{
		return get_option( $this->name );
	}

	public function save( $value )
	{
		update_option( $this->name, $value );
	}
}

class Admin_Post_Handler
{
	private $data;
	private $validator;
	private $post_field;

	public function __construct( Data $data, Request_Validator $validator, $post_field )
	{
		$this->data       = $data;
		$this->validator  = $validator;
		$this->post_field = $post_field;
	}

	public function update()
	{
		if ( ! $this->validator->is_valid() )
			die( 'nope' );

		$content = '';

		if ( isset ( $_POST[ $this->post_field ] ) )
			$content = $_POST[ $this->post_field ];

		$this->data->save( $content );

		wp_safe_redirect( $_POST['_wp_http_referer' ] );
		exit;
	}
}

new Controller;

Only briefly read over the code, but isn't there some sanitization missing?

Hi, i'm trying to get it work in my plugin. It work correctly whith one editor but if i add more, i get this issue:
second editor: http://i.imgur.com/nJB5hEq.png
first editor: http://i.imgur.com/oDMYGM5.png