texture painting 2.5 - hiding geometry

I’m trying to hide some geometry and I used to hit f and select the faces to hide - now when I hit f I can change the brush size - can anyone help me out?

I found a solution - just delete the parts that are blocking you in edit mode - paint - save - reload your model. Not ideal but I couldn’t figure out the little “Face selection masking for painting” button at the bottom of the painting window.