title: to initComponent() or not to initComponent()
body: <p>I struggle when building an app in ExtJS 4, and part of that is confusion on when to configure something in initComponent() and when not to...</p>
  
  <p>For example, in Sencha's own <a href="http://docs.sencha.com/ext-js/4-1/#!/guide/application_architecture">MVC Application Architecture</a> doc, when first creating the grid view, they defined the inline store in the initComponent() method.  (See "Defining a View" section)</p>
  
  <p>Further down, when they factored out the store into a separate class, they moved the definition outside of initComponent().  There is a helpful comment that draws attention to this fact, but there is no explanation.  (See Creating a Model and Store section)</p>
  
  <p>I guess the reason is supposed to be obvious, but I'm missing it.  Any pointers?</p>