I am a bit confused in what the application controller should do? Because I see the functionality will also exists in your MVP pattern to make the decisions which form should be shown when a button is clicked? Are there any good examples for Windows Forms that uses the application controller pattern?
There is a difference in the MVC(ontroler) and the Application Controller. I know the MVC(ontroller), I am not sure what is the responsibilities for an Application Controller, and how does it fit into a WinForms application. Martin Fowler also calls this the Application Controller pattern, surely it is not the same thing as the MVC(ontroller)?
I recently wrote an article on creating and using an ApplicationController in a C# Winforms project, to decouple the workflow and presenters from the forms directly. It may help:
Decoupling Workflow And Forms With An Application Controller
edit:
Archive.org has got a more readable copy of the article at this time.