A simplified version of http://bl.ocks.org/pbogden/7487564 made by pbogden. You can assign every button ‘click’ event to different functions:
var data = [{label: “BUTTON.A”, x: 100, y: 60, function: function(){ fnA(); } }, {label: “BUTTON.B”, x: 100, y: 120, function: function(){ fnB(); } } ];