This would be the clean way to express the current version of the code. However, I am still toying with the idea of allowing (sub)trees to synchronize on an object passed in as a parameter to the Node constructor. If the object reference is null, synchronization is turned off. In this scheme, I would allow subclasses (like Area) to switch synchronization on by setting the 'sync' object non-null, as, for example, when a locally constructed subtree was grafted onto the AreaTree. It also returns to the situation of a common synchronization object for each node in the (sub)tree.
The notion of switching synchronization on and off is, unfortunately, brain-dead. If synchronization is to be changed, then the code which changes and reads the synchronization state must itself be synchronized.
The conditional synchronization that I have now is only workable because the setting for any particular node is immutable.
Peter -- Peter B. West <http://www.powerup.com.au/~pbwest/resume.html>
