[Plugin: NextGEN Gallery] postboxes

I am duplicating some menus in order to add some extra functionality in this plugin. The core functionality is there, but I have a problem with postboxes.
In the nggallery-manage-gallery&mode=edit page, the gallery settings can open and close.
After I duplicated the code for my purposes, I can’t get this feature to work, as the script errors with ‘postboxes is not defined ‘

I was wondering where are those defined? I’ve searched the entire plugin directory and they only exist in the jQuery script within manage-images.php

jQuery(document).ready( function() {
	// close postboxes that should be closed
	jQuery('.if-js-closed').removeClass('if-js-closed').addClass('closed');
	postboxes.add_postbox_toggles('ngg-manage-gallery');

});

Also, I know this is connected to a wordpress option in the DB, but I don’t mind using one option for both gallery postbox and my extension.

thanks

http://wordpress.org/extend/plugins/nextgen-gallery/