* @return true if the update was successful, false otherwise.
     */
    public boolean updateAnnotation(Annotation annotation) {
        // bail on null annotations
        if (annotation == null) {
            return false;
        }

        // make sure the page annotations have been initialized.
        if (!isInited) {
            try {
                initPageAnnotations();
            } catch (InterruptedException e) {
                logger.warning("Annotation Initialization interupted");
            }
        }

        StateManager stateManager = library.getStateManager();
        // if we are doing an update we have at least on annot
        Vector<Reference> annots = (Vector)
                library.getObject(entries, ANNOTS_KEY.getName());

        // make sure annotations is in part of page.
        boolean found = false;
        for (Reference ref : annots) {
            if (ref.equals(annotation.getPObjectReference())) {
                found = true;
                break;
            }
        }
        if (!found) {
            return false;
        }

        // check the state manager for an instance of this object
        if (stateManager.contains(annotation.getPObjectReference())) {
            // if found we just have to re add the object, foot work around
            // page and annotations creation has already been done.
            stateManager.addChange(
                    new PObject(annotation, annotation.getPObjectReference()));
            return true;
        }
        // we have to do the checks for page and annot dictionary entry.
        else {
            // update parent page reference.
            annotation.getEntries().put(Annotation.PARENT_PAGE_KEY,
                    this.getPObjectReference());

            // add the annotations to the parsed annotations list
            annotations.add(annotation);

            // add the new annotations to the library
            library.addObject(annotation, annotation.getPObjectReference());

            // finally add the new annotations to the state manager
            stateManager.addChange(new PObject(annotation, annotation.getPObjectReference()));

            return true;
        }
    }