How to show that a class/interface is the interface of a package in ArgoUML

Suppose I have the following package represented in ArgoUML:

How could I emphasize that the User interface is the only component of the package that is known by external clients? For now, I use a note, but I think there should be a way of doing it more explicitly.

Note: it should be done in ArgoUML.

In UML, this is achieved using visibility: set the visibility to Public for "User" and to Package for the others.

ArgoUML (0.32.2), however, is unable to display visibility for elements (but it can display the visibility of packages themselves). There is an option for visibility in Settings - Notations, but it seems to have no effect.

An alternative is to be selective in what you show in a particular diagram. Say your diagram describes the API; it would then only include "User" from this package, along with relevant public classes and interfaces from other packages.

Since you're up against a limitation of the tool, I would include a note in any case.