Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/TreeBinding.java
private final IUpdatableTree target;
	private final IUpdatableTree model;
	private int updating = 0;  
	/**
	 * @param context
	 * @param target
	 * @param model 
	 */
	public TreeBinding(DataBindingContext context,