1) The docs for the layout code aren't in the same style & formatting for doxygen as the rest of the sources.
2) When you --enable-layout and generate the docs, the classes are not distinguished as being part of layout. You get things like CompartmentGlyph at the same level as Compartment and CompartmentType. We need to figure out how to group the layout docs. This is a more general issue having to do with how extensions will be handled in libsbml 4.