It's starting to become more widely supported to implement a hook_suppress($set = TRUE) that if triggered will not output anything 'special' that a module adds to a page (for us in modal callbacks, etc). This support is already implemented by admin_menu, admin, toolbar (via admin_select) and other modules. It would be good if we could universally support navbar as well. This hook is also used by the admin_select module to allow users to select the type of administration navigation they want to use if multiple options are available.
See related issues: