I've noticed playing FTL on Mac that you can't Alt-Tab in-game. I would describe this as a feature request or a bug but you can decide

I've noticed this to happen with other games in the past but I'm unsure how they fixed it. For example Blizzard had this problem with Starcraft 2 during the beta. There have been some other indie's I've noticed this too, but their names are lost on me.