Shoutbox

The ping will not result in a pong if the person is appearing offline, i tested that out

Also, the block/unblock thing with the name will not work if the person has you blocked, since messenger blocks contact signin toast for contacts that you have blocked, it would only work for people that are appearing offline

Also, when you keep changing your personal message and display name, etc, the notifier pops up saying that people have opened your window, sometimes. But not the contact that has you blocked.