While preparing for the course that I’m teaching at Adobe Max this year I ran into an issue when trying to add the site navigation as a Library item in Dreamweaver CC 2018. The option for “Add Object to Library” in Tools > Library is greyed out It turns out that you can not add an object to the library while in Code or Live view, you need to be in Design view with the item selected before the option presents itself. Once you have switched to Design View only the option to Add Object to Library becomes available