I would like to be able to custom theme a region for specific pages, is this possible? If so how?

For example I have a ragion called `rightbar` and I know the region can be themed using `region--rightbar.tpl.php` but is there a way of theming this using something like `page--node--1--region--rightbar.tpl.php`?

Or am I going to have to condition the `region--rightbar.tpl.php` script?