Hi Peter, here is a suggestion regarding the playlist button operation to create a smoother user operation, I would make this button behave this way, when you choose playlist the playlists appear for you to choose one , now as you have entered the actual playlist you have two options to get back to playlists and so far all this works and is great, as you hit playlist icon to return to playlists I WOULD MAKE IT SO WHEN YOU HIT THE SAME PLAYLIST BUTTON AGAIN IT RE ENTERS THE HIGHLIGHTED PLAYLIST AGAIN, this then simply toggles in and out of playlists no need to look and move your fingers to a different position to choose the same playlist, I know it seems pedantic but I just feel it is missing this as sometimes you just want to quickly flick between the two and having that flexibility on the same button would just streamline the workflow , I love the highlighted in use playlist change but feel the PLAYLIST button could be made to be more useful by allowing us to quickly tap it again to get back to the other window.
Small things perfected end up with big things LOVED.