Bug 174701 [Viewers] ViewerRow should be reused instead of connected to the Item
Currently we create a ViewerRow ver every Item we create this can degrade performance, we should cache the row and reuse it
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
treeListeners.remove(listener);
	}
	/**
	 * This implementation of reveal() reveals the given element or tree path.
	 */
	public void reveal(Object elementOrTreePath) {
		Assert.isNotNull(elementOrTreePath);
		Widget w = internalExpand(elementOrTreePath, true);
		if (w instanceof Item) {
			showItem((Item) w);
		}
	}
	/**
	 * Returns the rightmost visible descendent of the given item. Returns the
	 * item itself if it has no children.
	 * 
	 * @param item
	 *            the item to compute the descendent of
	 * @return the rightmost visible descendent or the item iself if it has no
	 *         children
	 */
	private Item rightMostVisibleDescendent(Item item) {
		Item[] children = getItems(item);
		if (getExpanded(item) && children != null && children.length > 0) {
			return rightMostVisibleDescendent(children[children.length - 1]);
		}
		return item;
	}
	
	public Item scrollDown(int x, int y) {