Gnome-terminal has been causing me grief since moving to Dapper. Moving through tabs is done with CTRL+Page Up or Page Down. However, when you reach the far left or far right you end up with the characters 5~ appearing on your screen. Even worse is when you are in vim when that is interpreted as switch the case of the next five characters.

This is an annoyance which has been bugging me, but only now was it annoying enough for me to go and hunt down the bug. The temporary solution: turn off your num lock key.