Is it OK to use qt_register_signal_spy_callbacks?

The function qt_register_signal_spy_callbacks will register functions that will be called before / after each signal emission, and before / after each slot call. Although TrollTech does not document this function. it appears that some test utilities use this function. It appears that this function is in a gray area: it is not documented, but it cannot be removed without impacting test software. This makes me wonder: is it safe to use the qt_register_signal_spy_callbacks function? Or should this be regarded as an implementation detail that can go away at any time?

If it is not documented, then it is to be used at your own risk - the function may change or disappear in future versions of Qt. I guess the test tool manufacturers are well aware that they might have to change their software in the future if this function should be dropped from Qt.