mvp for application with menutree

Hi, i'm just starting with GWT. First is started to build my app without MVP and now i see why they advise to use the MVP pattern and the eventbus.

I'm building an application with a DockLayout with on the west a treemenu and in the center a form. Which form to display depends on the selected menu item.

How kan i replace presenters (the different forms) in the center of the main DockLayout. Via an event?

And in the menu i want submenu items and those will select a (Dock)panel inside the center form pan.

The screen layout is like this (screen-layout.png):