Hello, there is a swarm of people asking for this in the official forums, but we both know blizzard ain't gonna implement it.
There were people asking for it since sept 2010, on starcraft2 forums; so well... this was possible to do in WoW cause it used a different connection for connecting to battle.net; but Blizzard clevertons now have made the game to work only 2 connections (both on 1119 port) one to the server you're playing, and one for logging/social/keeping yourself connected.
If i block the latter one after i'm in the server, i can keep playing but once every 120secs or something the game checks for social evidently, gets port closed and logs you out!
SO, yeah, need something more elaborate to hack what the game reads from the port
Anyone working on this?
PS: i won't even bother telling you why playing as invisible can be handy, without eventually removing all my friends on friendlist