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
private Object element;
        private Item item;
        UpdateItemSafeRunnable(Item item, Object element) {
            this.item = item;
            this.element = element;
        }
        public void run() {
            doUpdateItem(item, element);
        }
        
    }
    /**
     * Creates an abstract tree viewer. The viewer has no input, no content
     * provider, a default label provider, no sorter, no filters, and has
     * auto-expand turned off.
     */
    protected AbstractTreeViewer() {
        
    }
    /**
     * Adds the given child elements to this viewer as children of the given
     * parent element. If this viewer does not have a sorter, the elements are