Bug 135284 [Viewers] API: need to add methods to StructuredViewer to support ViewerComparator
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* resulting array must not be modified, as it may come directly from the
	 * model's internal state.
	 * 
	 * @param parent
	 *            the parent element
	 * @return a filtered array of child elements
	 */
	protected Object[] getFilteredChildren(Object parent) {
		Object[] result = getRawChildren(parent);
		if (filters != null) {
			for (Iterator iter = filters.iterator(); iter.hasNext();) {
				ViewerFilter f = (ViewerFilter) iter.next();
				result = f.filter(this, parent, result);
			}
		}
		return result;
	}
	/**
	 * Returns this viewer's filters.
	 * 
	 * @return an array of viewer filters
	 */
	public ViewerFilter[] getFilters() {
		if (filters == null) {
			return new ViewerFilter[0];
		}
		ViewerFilter[] result = new ViewerFilter[filters.size()];
		filters.toArray(result);
		return result;
	}