Confirm option on submit_tag -- not working

I'm getting an incorrect result with the confirm option of submit
buttons. This source...

      <%= button_to "Submit entire questionnaire", {},
        :confirm => "Are you sure? You will not be able to make any
more changes.",
        :id => 'button-submit-entire'
      %>

generates this html, whcih works fine...

<input id="button-submit-entire" onclick="return confirm('Are you
sure? You will not be able to make any more changes.');" type="submit"
value="Submit entire questionnaire" />

But this source...

    <%= submit_tag "Submit entire questionnaire",
      :name => :submit_submit,
      :id => :submit_submit,
      :class => :submit_nav,
      :confirm => "Are you sure? You will not be able to make any more
changes."
    %>

generates this html, which looks wrong and does not do the
confirmation...

<input class="submit_nav" confirm="Are you sure? You will not be able
to make any more changes." id="submit_submit" name="submit_submit"
type="submit" value="Submit entire questionnaire" />

Rails bug? My error?

Thanks. --David.

What version of Rails? Looks like 2.1 has this feature. 1.2.5 does not. (that's what I have local docs for, hence those versions).

-philip

Ahh... using 2.0.2. I had problems deploying in 2.1. OK, I'll build
it by hand -- not hard. Guess I'd better not use the 2.1 docs.

Thanks. --David.