public function register() 
    {
        add_action( 'admin_head', array( $this, 'add_filters' ) );
        add_action( 'wp_head', array( $this, 'add_filters' ) );
        
        if( is_array( $this->config['callback'] ) )
        {
            foreach( $this->config['callback'] as $handle => $callback )
            {
                $callback->register( $this->config['slug'].'_'.$handle );
            }
        }
        else
        {
            $this->config['callback']->register( $this->config['slug'] );
        }
    }