Plugin Development
This documentation applies to plugins for 1.x only!__
Documentation for 2.x+ is built into the Plugin Creator of Musescore.
( ⇒ In Musescore press Ctrl+Shift+P, then F1 to bring it up. )
Here is a brief guide to 2.x: Plugins for 2.x
And here the documentation for 3.x Plugins for 3.x