The Application Menu appears at the top of each page. It is a bar-separated list of links to application pages. If the current page is on that list, the corresponding link is disabled (that is, rendered as plain text).
The Sakai Style Guide 1.4 describes this as Intra-tool Navigation, but does not specify context-sensitive disabling of links.
Samigo has a similar page element, currently coded in-line on each page. CVS contains a NavigationMapTag which seems close to what's needed, but lacks support for disabling the current context.
APPROACH
Since the Sakai 2.0 Baseline Gradebook has a relatively small number of pages, we'll begin, like Samigo, by accepting the copy-paste-and-edit overhead. That is, we'll in-line the variant menus and statically include the invariant form when we can.
If a full-featured implementation of the Intra-tool Navigation component becomes available in time for us to integrate it without hurting our delivery schedule, we'll try switching to it.