Brian Lloyd writes:

The realm is currently an attribute of the RESPONSE object. .... Note that wouldn't help with "per folder" realm changing. I'm open to suggestions on that. One way I suppose would be to subclass Folder and implement an extended version of __bobo_traverse__ that changed the realm upon traversal. Or (ab)use the SiteAccess product (an external method as AccessRule setting the RESPONSE's realm attribute.

Dieter