How can the king's dresser be of any use?

Hint 1 of 12:

First of all, you should take the music box that is on the dresser.

Hint 2 of 12:

Then explore the dresser itself.

Hint 3 of 12:

The drawers hold nothing of importance at this point, until you discover
another object.

Hint 4 of 12:

Look at one side of the mirror; there is a note.

Hint 5 of 12:

The note reads something about "open up, don't shut down, go right in, don't
be left out" or something like that.

Hint 6 of 12:

Could this carry over to anything within the vicinity?