The piano in the witch's house has the keys C to upper B. Upon clicking a key the sound is played and the chat window says Play a [note]. In playing mode it's possible to click the secret compartment. When the secret compartment is clicked, it says The compartment seems to be locked. You can't open it. It can, however, be opened by playing according to the music sheet. When opened, players will find a to-do list, a shrinking recipe and two shrunk ogleroots.