@Override
		public void handleEvent(Event event) {
			Rectangle treeBounds = new Rectangle(0, 0, 0, 0);
			Point treeSize = tree.getSize();
			treeBounds.width = treeSize.x;
			treeBounds.height = treeSize.y;
			TreeItem[] rootItems = tree.getItems();
			for (int i = 0; i < rootItems.length; i++) {
				TreeItem rootItem = rootItems[i];
				System.out.println(rootItem.getText() + " is at least partially visible? " + treeBounds.intersects(rootItem.getBounds()));
				TreeItem[] childItems = rootItem.getItems();
				for (int j = 0; j < childItems.length; j++) {
					TreeItem childItem = childItems[j];
					System.out.println(childItem.getText() + " is at least partially visible? " + treeBounds.intersects(childItem.getBounds()));
				}
			}
		}