Hm... this doesn't appear to work on OSX (in iTerm, at least). I wonder what's going on.

concurrent-output should work on terminals that support ANSI escape sequences for cursor movement. I've tested it on several terminals on Linux, but have no access to OSX. It also works on Windows due to the portability layer in ansi-terminal. --Joey

Version 1.6.1 avoids using some ANSI codes that are not widely supported, and I think will work on OSX. --Joey