You will notice that navigationContent, actionContent, and the Spark components are defined in MXML. Within each, I have included a Button. Each Button has a clickHandler that includes a call to one of the navigator methods. The Button labeled "Home" has a click Handler that includes a call to the popToFirstView() method, which will always send the user back to the view defined in the firstView property of the ViewNavigation Application. The Button labeled "Back" has a clickHandler that includes a call to the popView() method, which will always send the user to the previous view in the stack.
Developing Android Applications with Flex 4.5 by Rich Tretola