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
internalSetExpandedTreePaths(expandedTreePaths, getControl(), new TreePath(new Object[0]));
    }
	/**
     * Sets whether the node corresponding to the given element or tree path is expanded or
     * collapsed.
     * 
     * @param elementOrTreePath
     *           the element
     * @param expanded
     *           <code>true</code> if the node is expanded, and <code>false</code>
     *           if collapsed
     */
    public void setExpandedState(Object elementOrTreePath, boolean expanded) {
        Assert.isNotNull(elementOrTreePath);
        Widget item = internalExpand(elementOrTreePath, false);
        if (item instanceof Item) {
            if (expanded) {
                createChildren(item);
            }
            setExpanded((Item) item, expanded);
        }
    }
    /**
     * Sets the selection to the given list of items.
     * 
     * @param items