Shuffle...jumps around and plays music from your iTunes library, or plays music from a music chest.
Shuffle button. This will allow you to randomly play music from a Music Chest drawer or from all of the music on your device. All of the music on your device is referred to as iTunes.
Why does it let you choose? Most people have piano music mixed in with their regular mp3 library. This way you can keep them separate.
After you touch the button, this drop down menu appears. You can then choose between iTunes and a Music Chest drawer.