Opening several tabs at once no longer leaves some of them stuck connecting when their servers need a host key confirmation.
In 1.6.3, when more than one tab hit an unknown or changed host key at the same time, Serverus asked about only one of them. The other tabs kept trying to connect without ever showing a question, and had to be closed and reopened one by one. Now each server is asked about in turn, and the dialog shows how many more are waiting. Tabs that connect to the same server with the same key share a single confirmation.
The confirmation's buttons become active half a second after it appears, so a double click on one confirmation can't accept the next server's key before you've seen it.