Shoutbox

when a contact goes offline and his name is selected, the contacts window move the scroll bar, seeking that contact

I'm not sure if I fully understand what your saying..

Do you mean that when you click on a contact so it's highlighted on the contacts list, and when the contact goes offline, it moves down the list and the scrollbar therefore moves?

If so, this has nothing to do with Messenger Plus! Live and I don't think it's a bug. If the contact is highlighted and they go offline, it should still be highlighted, that's normal. When something is highlighted, you can always see it, right?

If what Chris said was true, then this problem lies with the messenger itself. Whenever a contact sign out, and you have highlighted that particular contact, you will be "moved with it". As I think the program will follow your actions, and perhaps it (the program) thinks that you still want to chat/leave an offline message for that highlighted contact.
This mightn't be a bug, and might have done it intentionally. As when I used the beta version of the messenger (WLM), this "problem" occurs too.