I have a <form> element surrounding several inputs:
<form>
  <div class="tr" id="widget306">
    <div class="td col-grab">
        <button type="button" class="button grab formwidget" id="widget611">m</button>
    </div>
    <div class="td col-name">
        <input type="text" name="name" value="target volume profile 1" id="widget607" class="formwidget textbox">
    </div>
    <!-- ... etc ... -->
  </div>
</form>
I would like to trigger a submit event on the form when the user presses enter while focused on an element (standard behavior for input elements wrapped in a <form> tag), but when I press enter, nothing happens (fiddle).  If I remove all but one input element, the code works, and I get the expected behavior of pressing enter and triggering a form submit (fiddle).
How do I get the desired behavior (pressing enter submits the form) in the first example where I have multiple forms?
Note: I have found this same behavior in Safari 5.1, Chrome 17, Firefox 9, and IE 9.
Clarification: I know I can just throw some Javascript at it, but I'd like solve it with just markup.
Update: as some of you have helpfully pointed out, I can get the desired behavior by adding an <input type=submit>.  The problem is I don't want the user to see the submit button.  I can't just set its display to none, because then browsers won't submit when return is pressed, so I borrowed from QUnit and set the following:
HTML:
<input type=submit class=hide-me />
CSS:
.hide-me {
  position: absolute;
  left: -10000px;
  top: -10000px;
}