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
* be collapsed.
     * <p>
     * This method is typically used when restoring the interesting state of a
     * viewer captured by an earlier call to <code>getExpandedTreePaths</code>.
     * </p>
     * 
     * @param treePaths
     *           the array of expanded tree paths
     * @see #getExpandedTreePaths()
     */
    public void setExpandedTreePaths(TreePath[] treePaths) {
        assertElementsNotNull(treePaths);
        final IElementComparer comparer = getComparer();
        IElementComparer treePathComparer = new IElementComparer(){
			public boolean equals(Object a, Object b) {
				return ((TreePath)a).equals(((TreePath)b), comparer);
			}
			public int hashCode(Object element) {
				return ((TreePath)element).hashCode(comparer);
			}};
        CustomHashtable expandedTreePaths = new CustomHashtable(treePaths.length * 2 + 1, treePathComparer);
        for (int i = 0; i < treePaths.length; ++i) {
            TreePath treePath = treePaths[i];
            
            
            
            
            internalExpand(treePath, false);
            expandedTreePaths.put(treePath, treePath);
        }