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
* The default implementation of this framework method calls <code>hasChildren</code>
     * on this viewer's content provider. It may be overridden if necessary.
     * </p>
     * 
     * @param element
     *           the element
     * @return <code>true</code> if the tree node representing the given
     *         element can be expanded, or <code>false</code> if not
     */
    public boolean isExpandable(Object element) {
        ITreeContentProvider cp = (ITreeContentProvider) getContentProvider();
        return cp != null && cp.hasChildren(element);
    }
    
    protected void labelProviderChanged() {
        
        Control tree = getControl();
        tree.setRedraw(false);
        
        internalRefresh(tree, getRoot(), false, true);
        tree.setRedraw(true);
    }
    /**
     * Creates a new item.
     * 
     * @param parent
     *           the parent widget
     * @param style
     *           SWT style bits
     * @param index