Bug 79916 [Viewers] isDisposed check needed in AbstractTreeViewer#internalRemove
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* child already exists do nothing.
     * @param widget
     * @param element
     */
    private void createAddedElement(Widget widget, Object element) {
        if (equals(element, widget.getData()))
            return;
        Item[] items = getChildren(widget);
        for (int i = 0; i < items.length; i++) {
            if (items[i].getData().equals(element)) {
            	
            	refresh(element);
                return;
            }
        }
        int index = indexForElement(widget, element);
        createTreeItem(widget, element, index);
    }
    /**
     * Returns the index where the item should be inserted.
     * 
     * @param parent
     *           The parent widget the element will be inserted into.
     * @param element
     *           The element to insert.
     * @return int
     */
    protected int indexForElement(Widget parent, Object element) {
        ViewerSorter sorter = getSorter();
        Item[] items = getChildren(parent);