So far, it is 4.2, but we don't use new Eclipse 4 features. So we
rely on what you call "compatibility mode", that is 3.x APIs (which
are still used by all Eclipse projects so far).
Moving to Eclipse 4 application model to use its improvements will
require an investment to move JBDS application to the E4Application
pattern. This effort is not yet planned. This is to be discussed
with Max when he gets back from his holiday.