Show the last X recently edited files in a dashboard widget

dashboard_widget_recently_edited_files.php

<?php
defined( 'ABSPATH' ) OR exit;
/**
 * Plugin Name: (#64910) (Dashboard Widget) Last edited files
 * Description: Lists the last edited files in a dashboard widget
 * Author:      Franz Josef Kaiser <[email protected]>
 * Author URL:  https://plus.google.com/107110219316412982437
 * License:     MIT
 */

if (
	( defined( 'DISALLOW_FILE_EDIT' ) AND DISALLOW_FILE_EDIT )
	OR
	( defined( 'DISALLOW_FILE_MODS' ) AND DISALLOW_FILE_MODS )
)
	add_action( 'plugins_loaded', array( 'file_mods_monitor', 'init' ) );

/**
 * Adds a Dashboard Widget that holds the last edited files
 * @package WordPress
 * @author  Franz Josef Kaiser <[email protected]>
 * @version 2012-23-12.1114
 */
class file_mods_monitor
{
	/**
	 * Instance of the object
	 * @static
	 * @var    \file_mods_monitor object
	 */
	protected static $inst;

	/**
	 * Number of files to show
	 * @var int
	 */
	public $num_files = 20;

	/**
	 * Init, instantiates the object
	 * @static
	 * @return \file_mods_monitor An instance of the object
	 */
	public static function init()
	{
		is_null( self :: $inst ) AND self :: $inst = new self;
		return self :: $inst;
	}

	/**
	 * Constructor
	 * @return \file_mods_monitor
	 */
	public function __construct()
	{
		add_filter( 'pre_update_option_recently_edited', array( $this, 'amount_files' ), 10, 2 );
		add_action( 'wp_dashboard_setup', array( $this, 'add_widget' ) );
	}

	/**
	 * Adds the widget to the dashboard
	 * @return void
	 */
	public function add_widget()
	{
		wp_add_dashboard_widget(
			 'recently_edited_files'
			,'Recently edited files'
			,array( $this, 'widget_content' )
		);
	}

	/**
	 * Show the last edited files
	 * Callback for wp_add_dashboard_widget()
	 * @return string
	 */
	public function widget_content()
	{
		$files = (array) get_option( 'recently_edited' );
		var_dump( $files );
		$table = new WP_List_Table( $files );
		$table->display();
	}

	/**
	 * Pre Option update callback to alter the amount of files
	 * saved inside the `recently_edited` option table entry.
	 * @param  array $new_val
	 * @param  array $old_val
	 * @return array $new_val
	 */
	public function amount_files( $new_val, $old_val )
	{
		return array_slice(
			 array_unique( array_merge( $new_val, $old_val ) )
			,0
			,$this->num_files
		);
	}
} // END \file_mods_monitor