How to set the context of a EmberJS component?

I found on this page a great example of http://ift.tt/26T9fEt how to inherits from a component. Here is the example: http://ift.tt/1Y88odc

I played a bit with and especially with actions and come to this question:

How can I set the context of the component?

Consider the following examples:

http://ift.tt/26T9fEv

and a derivate of it

http://ift.tt/1Y88odf

They are pretty much the same except that in the second link, the component is dynamically create inside an action.

My question is, why is in the second example a "generated application controller" and not a "App.XBarComponent"?