Interval quality and quantity in the Note Reading Trainer

From now on, quality and quantity will also be trained in the interval reading mode of the Note Reading Trainer.
After selection of quality and quantity from the buttons below the staff, the selection has to be submitted by clicking on 'Check selection'.
The design is, admittedly, a little rough around the edges. It works without errors and bugs though (as far as I can tell).

At this moment, only the first note can have an accidental. This means that not all combinations of quality and quantity are going to be displayed. At least that's the case as I understand it, as my skills in music theory are lacking still.
Accidentals for the second note will follow soon.

As I mentioned, a redesign is needed as well. Especially the interface of the interval reading mode is a little too cramped. If all goes well, the changes will go live in the coming days.

The Note Reading Trainer can be found here (or under Tools ⟶ Note Reading Trainer).