> Imho this is not a protocol issue, but a client issue This has been discussed in length before, and the conclusion was that there is no user friendly *and* correct way to do invisibility on top of privacy lists, or any kind of simple operation (such as blocking). Psi has a 'simple' user interface for blocking contacts on top of privacy lists, but if you used *any* other client to do some privacy list operation, then it could break this. We show a warning 'your list may not work', but this is just a horrible user experience. And things get even nastier if you do invisibility, with all kinds of problematic corner cases.
Maybe you should look up the original discussion. You cannot fully abstract something that is fundamentally complex. Sooner or later, a user of your abstraction will bump into a problem, and will not understand it unless he understands the concepts underlying your abstraction. cheers, Remko
