Thank you Chris!
Funny you'd mention left/right handed.
The first version had the hotspots which trigger the notes in the center of the app.
Because I tested on a desktop, I didn't realize how hard that would be for a thumb to reach when used on a mobile phone or tablet.
So yes, that is easy to implement and I don't see a reason why it wouldn't make it into the app.
On behalf of all left handed children who tackle music notation via this app, I thank YOU!