How to use inputTVtype for URL?

I'm trying to add a slider to my homepage and in the table for form tabs, I'm using {"field":"ButtonHREF","caption":"Button HREF","inputTVtype":"URL"}.

When this is in use in my TV, I'm getting a dropdown menu with protocol selections (--, http://, https://, ftp://, and mailto:) and also the field for the URL. This can be useful for other external links. But how can I just get a normal URL field so I can use typical resource tags like [[~123]]? Otherwise I output href values like "/--sitemap" instead of "/sitemap".

Or is there some way to add an extra parameter to the chunk that generates these? Something like a Snippet that searches for the "--" in the href and replaces it with ""? I've tried this with no success.

Or is there a way to add a "blank" option to the protocol dropdown menu in the ButtonHREF field for the TV?

Thanks in advance.