Floating call window (cant find setting in s7)

I think I am probably just being thick here as I am sure I had it enabled.

On my S5 I had a floating window whilst in calls that I could interact with (drag it around the screen, mute etc)

I can't for the life of me work out how to enable this on the S7? I have played with notification settings all sorts is it just not available? or am I simply being thick?

Download from this link