form_build_id must start with a letter for XHTML compliance

Isn't it nicer todo:

-      $form_build_id = md5(mt_rand());
+      $form_build_id = 'form-'. md5(mt_rand());

instead of:

-      $form_build_id = md5(mt_rand());
+      $form_build_id = 'f'.md5(mt_rand());

Just my $0,02..

Set better title

Yes, we should make this change.

I agree that 'form-' is a better prefix.

Updated code, that works!

Committed! Thanks.

It is not clear to me why we are outputting an id field containing a randomly-generated hash in the first place. How can it ever be useful? Scripting, I guess.

For the record, we do this because it allows us to identify, via the incoming $_POST data, what specific version of a form is coming in. Not just the form's identification (like, 'node-story-form') but the specific instance of that form, built on a particular page at a particular time for a particular user.

This is particularly useful when AJAX code is making client-side modifications to a form; it can relay information back to the server to keep the server side validation code in sync with the client side form, for that particular instance.

Thanks for the clarification, I misread your post. You are correct that the hidden field serves that purpose.