General: convert tabs to spaces only if soft tabs?

[aseemk]

Generalized version of issue #14: is there a way to scope the convert-tabs-to-spaces command to only run if the current file's setting is soft tabs?

Some projects (unfortunately =P) use tabs instead of spaces, and that's always a pain since my instinct of saving with cmd+S converts those tabs to spaces. It'd be great if those could be auto-detected. =)