There is a patch here:
http://code.google.com/p/shellinabox/issues/detail?id=202

There may be a fix upstream:
https://code.google.com/p/shellinabox/

I tried to investigate this issue (make sure jiffylab hasn't already fixed this yet), but can't actually get jiffylab to run at all right now.

Current solution is "don't use Firefox"