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
* @param expandedTreePaths
     *           the set (element type: <code>TreePath</code>) of elements
     *           which are expanded
     * @param widget
     *           the widget
     */
    private void internalSetExpandedTreePaths(CustomHashtable expandedTreePaths, Widget widget, TreePath currentPath) {
        Item[] items = getChildren(widget);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            Object data = item.getData();
            TreePath childPath = data==null ? null: currentPath.createChildPath(data);
            if (data != null && childPath!=null) {
                
                
                boolean expanded = expandedTreePaths.remove(childPath) != null;
                if (expanded != getExpanded(item)) {
                    if (expanded) {
                        createChildren(item);
                    }
                    setExpanded(item, expanded);
                }
            }
            internalSetExpandedTreePaths(expandedTreePaths, item, childPath);
        }
	}
    /**
     * Return whether the tree node representing the given element can be
     * expanded.
     * <p>