[TxMt] Spaces instead of tabs -> per filetype basis?

Hey all,

I was wondering if there was a way to setup different file types to use the "Tab -> space" conversion feature, and others... not.

I.e. for Ruby on Rails code (.rb and possibly .rhtml), I'd like to have Tabs automatically get converted to spaces.

But for .txt files and other file types where I would like to keep tabs... is there a way to do this somehow?

Just finally registered my copy of TextMate... and, knowing how incredibly versatile it is, I'm just figuring there's got to be a way to pull this off somehow (w/o making it a new feature, which, imho would be nice too!) =)

Shanti