This plugin is a variation of RichHelms Concertina Tablature plugin. I modified it for obtaining a diatonic G/C 25 keys Hohner Galaad accordion tablature plugin.
This is the 1st version, it will certainly evolve ... I tested it with MuseScore 1.2.
As I am not able to write a JS plugin by myself, I am looking for somebody able to help me to develop this plugin in order to get the same result for all the staffs of a multi-staff system score (see example).