Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/provisional/databinding/ITree.java
* 
 * @since 3.2
 * 
 */
public interface ITree  {
		
	/**
	 * This is a helper class for ITree implementors and simplify the change notification
	 * handling.
	 * 
	 * @since 3.2
	 *
	 */
	public static class ChangeSupport {
		private ITree source;
		private List listeners = null;
		
		/**
		 * @param source tree
		 */
		public ChangeSupport(ITree source){
			this.source=source;
		}
		
		/**
		 * @param listener
		 */
		public void addTreeChangeListener(IChangeListener listener) {
			if (listener!=null) {
				if (listeners==null) {