GNU Smalltalk supports both file based and image based development. Exporting source files is no means to an end — image based development is not widespread because it forces people out of emacs and vim.
In the mid to late 90's, Smalltalk was still going strong. (It still is by some accounts.) I used GNU Smalltalk back then and it was pitifully gimpy in comparison to the commercial environments.
If you want to check out Smalltalk, check out Squeak or Pharo. You can also download VisualWorks noncommercial.
Also, to be fair, GNU Smalltalk has come a long way since then.
If you're running a windows machine, I found Dolphin pretty enjoyable (if the noncommercial edition is still available, i believe they're working on their next generation but x6 was pretty nice)