Bug 125272 [Viewers] AbstractTreeViewer needs remove(Object parentElement, Object[] childElements)
There is an add(Object parentElement, Object[] childElements) but no corresponding remove(). Without this method, if you have an element that appears under multiple parents, the only way to get model and viewer in sync after removing the element from just one of its parents is calling refresh().
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
protected void internalExpandToLevel(Widget widget, int level) {
        if (level == ALL_LEVELS || level > 0) {
    		createChildren(widget);
            if (widget instanceof Item)
                setExpanded((Item) widget, true);
            if (level == ALL_LEVELS || level > 1) {
                Item[] children = getChildren(widget);
                if (children != null) {
                    int newLevel = (level == ALL_LEVELS ? ALL_LEVELS
                            : level - 1);
                    for (int i = 0; i < children.length; i++)
                        internalExpandToLevel(children[i], newLevel);
                }
            }
        }
    }
    /**
     * Non-recursively tries to find the given element as a child of the given
     * parent item.
     * 
     * @param parent
     *           the parent item
     * @param element
     *           the element
     * @return Widget
     */
    private Widget internalFindChild(Item parent, Object element) {
        Item[] items = getChildren(parent);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];