WiFi Only option in GL3?

Is there a wifi only option in GL3? I haven't been able to find it. GL2.5 has it, which is a must for those of us with a limited data plan. I've found that GL3 uses about 2MG of data just by opening it. Is that some kind of automatic sync?

It seems to just work that way by default in 3.0. It seems to prompt you to temporarily enable cellular data if you attempt to download content when not connected to wifi. That does not appear to apply to video or syncing however -- only for content downloads.