I have the same problem, let say that you define a basic function in the aplicación, it ask you in the component config 2 things: fn and param

Then in the code of thet function you put what is the function and if you see the code will be like this:

Ext.Loader.setConfig({    enabled: true

    views: [

    autoCreateViewport: true,

    name: 'MyApp',

    launch: function() {


    mensaje: function(texto, texto2) {
        function mensaje (texto,texto2) {console.log(texto+" "+texto2)};

So you have the function mensaje defined in your app,

The question is how you can call your function?