Bug 111631 [Viewers] TreeViewer needs more TableViewer API
As the TreeViewer is meant to replace the TableTreeViewer we need to add some of the API that the TableViewer had to it so that it can be used like a table. public void insert(Object element, int position) public void add(Object[] objects) Both need to be added.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* Returns the item before the given item in the tree, or <code>null</code>
     * if there is no previous item.
     * 
     * @param item
     *           the item
     * @return the previous item, or <code>null</code> if none
     */
    protected Item getPreviousItem(Item item) {
        
        
        Item parent = getParentItem(item);
        if (parent == null) {
            return null;
        }
        Item[] siblings = getItems(parent);
        if (siblings.length == 0 || siblings[0] == item) {
            return parent;
        }
        Item previous = siblings[0];
        for (int i = 1; i < siblings.length; i++) {
            if (siblings[i] == item) {
                return rightMostVisibleDescendent(previous);
            }
            previous = siblings[i];
        }
        return null;
    }
    
    protected Object[] getRawChildren(Object parentElementOrTreePath) {
    	Object parent;