Ouch!

Looking at the source code as Firefox renders it, the problem becomes apparent immediately:

<form onsubmit="return validateDMPNameOnSubmit(this)" method="post" ac
+tion="/goform/formHandlerConfigureDMPName"></form>
<td width="5%">
<td width="45%">Digital Media Player Name:</td>
<td width="50%">
<input type="text" maxlength="129" value="mmmmmmmm" name="DMPName">
<input type="submit" value="Apply">
</td>
[download]

Firefox happily (and likely in accordance with some HTML specification) moves all the input elements outside of the form, as the form nastily spans across <td> elemenst without respecting their allowed nesting.

As WWW::Mechanize::Firefox relies on Firefox doing the heavy lifting, there is nothing I can do. Maybe you can work around things by specifying explicit XPath expressions to get at the respective DOM elements.

Your post highlighted another error - currently, ->form_with_fields will not respect <select> or <textarea> elements - this will be changed in the next version.