public function _order_callback( $plugin_a, $plugin_b ) {
		global $orderby, $order;

		$a = $plugin_a[ $orderby ];
		$b = $plugin_b[ $orderby ];

		if ( $a === $b ) {
			return 0;
		}

		if ( 'DESC' === $order ) {
			return strcasecmp( $b, $a );
		} else {
			return strcasecmp( $a, $b );
		}
	}