Here are some more findings on Ext.Application.

[1] The class docs is missing the @extends information which is why you don't see this info in the API docs.

[2] Throughout the framework the Ext.util.Observable is used as mixin, why doesn't Ext.Application follow the same path.

[3] The "profiles" still contains Phone and Tablet configurations. Is this Sencha Touch legacy?

[4] Ext.Application should really offer a mechanism for providing "Global Application Events". Since addEvents(..) is done in the constructor, it is difficult to extends the "events" for custom use, unless the idea is to subclass the Ext.Application.