Windows 7: Outline Editor that Naturally Handles OPML

OPML is a dialect of XML that is designed for outlines (it's also used for RSS feed lists and the like). It's not hard to find an outliner for windows (MS Word itself has a nice outline mode), but I haven't yet found (except for one seeming abandonware product) a Windows Outliner that reads/writes OPML natively. Even software like Bonsai has a python script or something that you have to use to convert it.

Does anyone know of a good outliner for Windows (or even a bad one) that can handle the OPML file format naturally (read/write), and is still being sold or maintained by someone?

hello, where you able to find a Windows outliner which can read/write to OPML without having to import / export?

thanks