Another possible source. I bought one of these about twenty years ago, and
I think they are still made.
You might try the Kirsch Co of Sturgis, Michigan. They make high quality
conventional curtain rods AND a product line called Architrac. The
Architrac is an extruded aluminum curtain rod which they can bend to most
any configuration. A drapery firm that caries Kirsch products can special
order it for you.
These curtain rods are typically used in hospitals and other commercial
installations. They even have draw curtain (dual track) versions too.
Naturaly, Kirsch has the slides to fit these rods.
Oliver Filippi