I know this is not a bug tracker but I found what seems to be just a typo error.

Line 4166 in latest nightly of zp-core/template-functions.php (Revision 6227):
there is a missing " after else echo 'none';?>

BTW, it would be nice to have the possibility to customize on theme basis the clear search icon, as it happens for the select search fields icon.

Well, the bug tracker would have been suitable for both. Anyway thanks, the typo will be fixed tonight and the request for the icon makes absolutly sense.

I had an account for the bug tracker but I can't find the password anymore.
I've added the possibility to customize the clear search icon, it seems to work on my test setup. I can give you the new file if needed.

Fixed in tonight's nightly and I also added a parameter for the clear icon similar to the other one.

Glad to be less noobie now. I did it exactly the same way!