To what widget are you referring? Do you mean the chat buddy list? Can you share a screenshot or the widget ID? Also, which version of Community are you using? I've noticed some of your questions are posted in the 10.x forum and this is the 9.x forum.
Unfortunately, this isn't a feature of 9.x. 10.x features a concept of user presence, but even in 10, it would require custom widget development expose that type of list.
