@texrat: Hmmm yeah, I didn't mean to do away with 'apps' and 'filesystems', at least not immediately..

...and I think this has more to do when you're interoperating multiple tasks from different apps and making use of objects from different media types. That's when the 'apps' and 'fs' boundaries show up and you'll have to change your thinking mode to 'cope' with this layer.

Working inside Visio is quite effortless as you don't need to deal with separate app or files (in general, unless you're importing medias or combinging multiple diagrams, i guess).