Enter key does not submit modal dialog form in IE with hidden submit input

In IE6, IE7 & IE8: If you have a modal dialog with a form and a hidden submit button (<input type="submit" style="display:none;"/>), the form will not submit or give any response. I found that if the submit button is visible and in the dialog, it works.

This is currently reproducible in the demo on jqueryui.com

As a workaround I used the following CSS to hide the submit button while keeping the enter key to submit working in IE

input.submit {
  background : white;
  border:none;
  float : right;
  height : 1px !important;
  margin-top : -20px;
  width : 1px !important;
}