How to detect System settings changes on device?

My WF is not behaving the same way on a device as it does in the simulator when System Settings (time format, language, units, etc) are changed.

In the simulator the WF gets called in onLayout which allows it to refresh using the new System Settings.  But on the device, onLayout is not called.

It seems that onSettingsChanged is called only if the WF settings changed but not when System Settings changed.

Is there another way to detect System Settings changes?  What am I missing?

Thanks,

Pete