Definitely needs to be an extension or external utility. I would opt for the latter, personally (especially if your profile is degrading under the newer TB versions). Already TB 102 can't see or browse to filesystem folders (it sees folders *within* the email profile just fine), and in addition the recent betas are showing blank panes if I open an existing profile. Doing an "import" of an old profile into a new one just makes the new profile just as problematic as the old one.