 	
 	// MARK: Double Split
 	
+	// Note about the Shim Controller
+	// In the root split view controller's secondary (or detail) position we use a view controller that
+	// only acts as a shim (or wrapper) for the actaully desired contents of the second position.  This
+	// is because we normally can't change the root split view controllers second position contents
+	// during the display mode change callback (in the split view controller delegate).  To fool the
+	// system, we leave the same controller, the shim, in place and change its child controllers instead.
+	
 	func installDetailController(_ detailController: UIViewController) {
 		let showButton = rootSplitViewController.displayMode != .allVisible
 		let controller = addNavControllerIfNecessary(detailController, showButton: showButton)

		}
	}
	
	@discardableResult
	func transitionToThreePanelMode() -> UIViewController {
		defer {

			
		} else {

			// Display a no selection controller since we don't have any detail selected
			return fullyWrappedSystemMesssageController()

		}
	}
