TRichEdit and Fonts

I am working on a Freeware Help File Editor and need some information as
to how some things can be don in a TRichedit.

How can one make text be double underlined?

How can one make text be invisible (in WinWord it looks like a dotted
underline)?

Can anyone please help me with this?

Would appreciate email response at gomc0...@stud.uni-sb.de since I
cannot always access the News groups.