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
int size = items.length;
		if (sorter == null)
			return size;
	    int min = lastInsertion, max = size - 1;
		while (min <= max) {
            int mid = (min + max) / 2;
            Object data = items[mid].getData();
            int compare = sorter.compare(this, data, element);
            if (compare == 0) {
                return mid;
            }
            if (compare < 0)
                min = mid + 1;
            else
                max = mid - 1;
	        }
	   return min;
	    
			
	}
	/**
     * Returns the index where the item should be inserted. It uses sorter to
     * determine the correct position, if sorter is not assigned, returns the
     * index of the element after the last.
     * 
     * @param parent The parent widget
     * @param sorter The sorter to use.
     * @param startIndex
     *            the start index to start search for position from this allows