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
Object[] children = getSortedChildren(parentElement);
                    for (int i = 0; i < children.length; i++) {
                        createTreeItem(widget, children[i], -1);
                    }
                }
            }
        });
    }
    /**
     * Creates a single item for the given parent and synchronizes it with the
     * given element.
     * 
     * @param parent
     *           the parent widget
     * @param element
     *           the element
     * @param index
     *           if non-negative, indicates the position to insert the item
     *           into its parent
     */
    protected void createTreeItem(Widget parent, Object element, int index) {
        Item item = newItem(parent, SWT.NULL, index);
        updateItem(item, element);
        updatePlus(item, element);
    }
    /**
     * The <code>AbstractTreeViewer</code> implementation of this method also
     * recurses over children of the corresponding element.
     */
    protected void disassociate(Item item) {