Kiwi is one of the many Twitter clients that have come out on Mac OS X. A client also complete and original, but which is unfortunately no longer actively developed. The developer has released a new beta version that fixes some bugs with Leo, but he does not spend time on its software in the future.
The reason is the poor relations with the social network developers. In March, Twitter launched a stir by questioning the value of Twitter clients. Since then, some developers worry a little that their work has been for nothing.
A recent change in the Twitter API has forced developers to change their applications under penalty of not to allow access to private messages.