plugin.js

Draw.loadPlugin(function(ui) {   
   // Adds action
   ui.actions.addAction('helloWorldAction', function() {
       var ran = Math.floor((Math.random() * 100) + 1);
       mxUtils.alert('A random number is ' + ran);
   });

   ui.actions.addAction('debugShapesAction', function() {
      mxLog.show();
      mxLog.debug("DEBUG");
      for (var i in mxGraph.prototype.getSelectionCells())
      {
        mxLog.debug(i);
      }
   });
   
   // Adds menu
   ui.menubar.addMenu('Hello, World Menu', function(menu, parent) {
       ui.menus.addMenuItem(menu, 'helloWorldAction');
       ui.menus.addMenuItem(menu, 'debugShapesAction');
   });
   
});