Mmmm, I had a quick look at at ``ScopedPreferenceStore`` and it doesn't look thread-safe. It contains a lot of mutable and non-final fields. 

It's also fishy that the JavaDoc of  ``ScopedPreferenceStore`` doesn't mention thread-safety (this is not enough to prove that the class isn't thread-safe, but given Eclipse documentation is usually good, I think it might be an indication). Indeed, if you look at the ``EventManager`` JavaDoc ( ``ScopedPreferenceStore`` is a subtype of  ``EventManager``), it is clearly stated that *All the methods on this class are guaranteed to be thread-safe.*.