Control navigation with hardware keys

What is the easiest way to navigate between controls with the hardware keys?

I know how to catch them but has someone created a generic routine to move between controls in a certain tab order.

I love Basic4PPC but the UI stuff is really tricky sometimes.

I've attached code that adds the focus event to all required controls with the door library and also allows you to determine the order of controls.
Navigation is done with two regular buttons instead of the hardware buttons. You can of course change it to use the hardware buttons.