Hiding Mobile Friends

I have a lot of friends who use the mobile app, and quite frankly i wish there was a way to hide them. I don't intend to message people who are offline, and I get kind of disappointed when I see 4 or 5 people online, but in reality it's just the mobile app. Something along the lines of the "Show Offline Friends" button in the options tab would be a nice change. People who don't like seeing mobile friends could turn it off and people who want it on could keep it on.