The culmination of recent changes to the KryptonNavigator and KryptonToolkit have allowed me to implement the Outlook mode.
You can now see why I added the Stack set of modes to the navigator and the HighProfile separator style drawing to the toolkit. Putting those together we get the Outlook appearance.

When you use the separator to shrink down the stacking items they are placed on the overflow bar at the bottom of the control.

The drop down button on the overflow bar is used to provide the same options as presented in Microsoft Outlook itself. The abililty to select which pages are visible or invisible and alter which items are on the stack or on the overflow bar.
I have added an event that is fired when the drop down button is pressed so you can customize the context menu that is shown or even provide your own instead. Alternatively you can hide the drop down button entirely if using a property on the navigator.
Once I have finalised the design time support I can then move onto adding some other, much requested, navigator modes.