One page application, how many views ?

Hello

I'm fairly new to ExtJS's MVC concept and I plan to do a one page application. A navigation menu's buttons will simply hide and show windows with whatever items they'll have.

From there, I am a bit confused as how many views I will need.

The view "Viewport.js" seems to be used to declare all views and host methods that create them. In this example, "createSearchBar" for create the view that holds the search bar.

But this example shows all views at once all rendered into the viewport.

How one would handle showing and hiding views to give the illusion of browsing from page to page and what needs to be done in MVC for this to be done as per best practices ?