i was playing around with TS3 a little bit and found out that you are able to connect to the same server more than one time simultaneously (which is intended, i guess).
I kicked one of these instances from the server and wanted to close the corresponding tab after this. Although the kick was already performed, a prompt appeared, telling me: You are still connected to No server. Close tab? This only happens when clicking on the "X" of the tab but not when using the "close tab" option from the context menu.
Another funny behaviour when connecting to the same server twice (or more often) is that you are able to add yourself to your buddy list which is not intended, i guess.