Please, dismiss everything.
reading ad_form references, i found that hidden is a widget, instead of a datatype as it is on html code.
ex:
input type="hidden" size="30" ....
So nothing more logical that replacing in the api
auth::get_registration_form_elements (public)
at packages/acs-authentication/tcl/authentication-procs.tcl
the url and screen_name widgets in the array. From text-url to hidden.
There you go. The fields are gone from the UI and still working in the system, in case we need to use the in the future.
