Moving meta boxes with WP_Content editors

gistfile1.php

/**
 * Moves meta boxes in the 'normal' context to the front of the 'advanced' context.
 * To be used when inserting content via the edit_form_advanced hook (example given)
 */
class MoveMetaBoxes {

	public $CPT_Slug = 'tdd_library';

	function __construct() {
		add_action( 'edit_form_advanced', array( $this, 'edit_form_advanced' ), 1 );
		add_filter( "get_user_option_meta-box-order_$this->CPT_Slug", array( $this, 'move_meta_boxes_to_advanced' ), 10, 3 );

		// This is the only way to get cascading priority, but really should be more targeted to the CPT_Slug. Further investigation needed
		add_action( 'admin_head', array( $this, 'collapse_normal_sortables_area' ) );
	}

	/**
	 * Filters the sort order of meta boxes.
	 * This is run just before they output for the first time. We will remove all the boxes
	 * From 'normal' and add them to 'advanced'
	 * Advanced metaboxes shows up below 'edit_form_advanced'
	 * @param $order array array for each meta box context with a string of meta box ids
	 * @param $param
	 * @param $user user object
	 * @return array with the modified order and an empty 'normal' key
	 */
	function move_meta_boxes_to_advanced( $order, $param, $user ) {
		if (isset( $order['normal'] )) {
			$order['advanced'] = join( ',', array( $order['normal'], $order['advanced'] ) );
			$order['normal'] = '';
		}
		return $order;
	}

	/**
	 * Override the minimum height for sortable areas
	 * Even if there are no metaboxes, there is still a min-height of 50px so
	 * that there is a drag target. We don't want anyone to drag stuff here, but
	 * We'll not display:none it just in case a metabox sneaks in there via
	 * some seriously messed up code.
	 * @return void
	 */
	function collapse_normal_sortables_area( ) {
		?>
	<style type="text/css">
		#post-body #normal-sortables { min-height: 0 }
	</style>
	<?php
	}

	function edit_form_advanced() {
		global $post;
		if ( $post->post_type == $this->CPT_Slug ) {
			wp_editor( 'default content', 'editor_id' );
		}
	}

}
$move_meta_boxes = new MoveMetaBoxes();