The fix for JDK-8080395 introduced new public API for getting the cause of a FocusEvent. It also removed (by making package-private) sun.awt.CausedFocusEvent, which caused exceptions in JFXPanel (see JDK-8156591).

The fix for JDK-8156591 commented out the calls to sun.awt.CausedFocusEvent. Once we upgrade to a newer boot JDK that includes the new FocusEvent.getCause() API we can use the new API and uncomment the code that determines the focus cause. This is a low-priority bug, since the focus cause is currently unused, so there are currently no functional problems in leaving the code commented out.