Bug 164509 Breaking API change: ColumnViewer#getItemAt(Point)
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*            subtrees are ignored
	 * @return the next item, or <code>null</code> if none
	 */
	protected Item getNextItem(Item item, boolean includeChildren) {
		if (item == null) {
			return null;
		}
		if (includeChildren && getExpanded(item)) {
			Item[] children = getItems(item);
			if (children != null && children.length > 0) {
				return children[0];
			}
		}
		
		
		Item parent = getParentItem(item);
		if (parent == null) {
			return null;
		}
		Item[] siblings = getItems(parent);
		if (siblings != null) {
			if (siblings.length <= 1) {
				return getNextItem(parent, false);
			}
			for (int i = 0; i < siblings.length; i++) {
				if (siblings[i] == item && i < (siblings.length - 1)) {
					return siblings[i + 1];
				}
			}
		}