Why does melody section highlight different scale degrees than the piano instrument?

The following question came in through email:

I have been playing on the Hookpad after reading the Hooktheory I to experiment with certain chords, I really enjoy it and find it very useful, However I have several questions which have been at the back of my mind regarding the Hook pad;
I have attached an image of what I am trying to explain to attempt to make it clear for you because I might not be able to explain this to the best of my knowledge. (Excuse my mouse painting)
When playing a iii Chord of C major, the B Drops down an octave on the piano but not on the midi roll
Could you please clarify this for me because it is really confusing?

In Hookpad, the piano displays chords the way Hookpad has decided to voice them. Take an E Minor chord, for example, from your graphic. There are many ways to play an E Minor chord on the piano. As long as you play an E in the bass and a G and B somewhere above the bass, then you are playing E Minor. Hookpad has decided to play the chord: E B G E. But if instead you wanted to play: E E G B, that’s perfectly fine as well.

In the Hookpad melody region, all of the stable scale degrees of a chord are highlighted, regardless of the octave. This is because when you are composing a melody, scale degrees 3, 5, and 7 (or E, G, and B in the key of C major) these are the notes that will sound the best over the iii (or E Minor) chord. In the above example, I’ve expanded the melody region to 3 octaves, and you can see, all 3s, 5s, and 7s are highlighted in every octave.