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
}
        }
    }
    /**
     * Recursively collects all expanded items from the given widget.
     * 
     * @param result
     *           a list (element type: <code>Item</code>) into which to
     *           collect the elements
     * @param widget
     *           the widget
     */
    private void internalCollectExpandedItems(List result, Widget widget) {
        Item[] items = getChildren(widget);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            if (getExpanded(item)) {
            	result.add(item);
            }
            internalCollectExpandedItems(result, item);
        }
    }
    /**
     * Tries to create a path of tree items for the given element or tree path.
     * This method recursively walks up towards the root of the tree and in the
     * case of an element (rather than a tree path) assumes that
     * <code>getParent</code> returns the correct parent of an element.
     * 
     * @param elementOrPath
     *           the element