Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/TreeBinding.java
IUpdatableTree target, IUpdatableTree model) {
		super(context);
		this.target = target;
		this.model = model;
		
		target.addChangeListener(targetChangeListener);
		model.addChangeListener(modelChangeListener);
	}
	private IChangeListener targetChangeListener = new IChangeListener() {
		public void handleChange(ChangeEvent changeEvent) {
			if (updating != 0  && changeEvent.getChangeType()!=ChangeEvent.VIRTUAL) {
				return;
			}
			if (changeEvent.getChangeType() == ChangeEvent.VERIFY) {
				
			} else {
				update(model, target, changeEvent);
			}
		}
	};
	private IChangeListener modelChangeListener = new IChangeListener() {
		public void handleChange(ChangeEvent changeEvent) {
			if (updating != 0  && changeEvent.getChangeType()!=ChangeEvent.VIRTUAL) {
				return;
			}
			if ((changeEvent.getChangeType() &  (ChangeEvent.CHANGE | ChangeEvent.REPLACE | ChangeEvent.VIRTUAL)) != 0) {
				update(target, model, changeEvent);
			}
		}
	};