How to retrieve the runtime stack of widgets

Our application has one top level QWidget and a bunch of children QWidgets, the children widgets may get raised/lowered/hidden/shown based on the states. We would like to get a list of QWidgets that's sorted by their actual positions in the window/widget stack in order to present the UI state for test automation. I couldn't find anything suitable in the Qt documentation, does anyone know how to get that kind of information?

BTW, this is for Qt 4.7.1

Thanks..