There used to be a Readme about the way libmscore worked. I saw it when musescore was on its way to 3.0.
Is there any newer version?
Else, is there anyone that would take the time to kindly explain it to me?
I was starting to dig through it to fix #215016: Allow measure numbers to appear below the staff, and couldn't quite get how it works. How do I add properties? Where are generic properties, like the placement (above or below staff), and their logic coded?