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
super.setSelectionToWidget(selection, reveal);
		}
	}
    /**
     * Returns a list of tree paths corresponding to expanded nodes in this
     * viewer's tree, including currently hidden ones that are marked as
     * expanded but are under a collapsed ancestor.
     * <p>
     * This method is typically used when preserving the interesting state of a
     * viewer; <code>setExpandedElements</code> is used during the restore.
     * </p>
     * 
     * @return the array of expanded tree paths
     * @see #setExpandedElements
     */
    public TreePath[] getExpandedTreePaths() {
        ArrayList items = new ArrayList();
        internalCollectExpandedItems(items, getControl());
        ArrayList result = new ArrayList(items.size());
        for(Iterator it = items.iterator(); it.hasNext();) {
        	Item item = (Item) it.next();
        	TreePath treePath = getTreePathFromItem(item);
        	if (treePath != null) {
        		result.add(treePath);
        	}
        }
        return (TreePath[]) result.toArray(new TreePath[items.size()]);
    }
}