When a select form element does not have "-None-"/"-Select-" options, nothing is saved as an option and when the form is reloaded all the options appear selected.

This happens in two places I've seen so far, one is the NAT admin page, and Views exposed filters. There are previous seprate issues for both, but we should focus on making a fix that would solve all this cases.

Issue #348424: Breaks Exposed Filters in Views 2
Issue #721068: Better Select not compatible with Node Auto Term (NAT) module

I don't understand on what cases the fAPI doesn't add the "-None-"/"-Select-" options, any help understanding that would be greatly appreciated.