IMs and FB

I'm not sure, exactly, how the Facebook thing works when it shows that you're online and (possibly) using Facebook.  I think that if you never close out your browser (like me) that it shows you are always on at Facebook.  In reality, I might pop into Facebook ten minutes a day, a few minutes here and there.

I mention this because I get a lot of IMs via FB from people who must think I am online.  I usually try to respond, and if I'm not busy, I can chat a few lines.  Please don't be offended i...