Feature Request: Use arrow keys to increase number values

[octavo]

Use arrow keys to increase number values when cursor is in the input field.

[Secret-chest]

And add spinbox arrows to make them funner to use.

[eno32]

Hi! I am currently a student at the University of Michigan and I am looking to make this change for a class project. I am not sure where to make this change and have been looking through all the files for a few days. Can anyone point me in the right direction?