Absent status [Online, Absent, Offline]

Sometimes I see that one friend is "online" and then i talk him but... there's no answer. It is because I see the green button (online) and I think that she/he is online, but the truth is she/he is not. Maybe because she/he is going to the bathroom, or maybe having lunch (for example), so I think that if a person can take the "Absent" status, we would know that this person could be there soon. Think about it.