* @param target
* @return true if descendant, otherwise false
*/
private boolean isDescendant(Object source, Object target) {
if (source instanceof Folder) {
final Folder folder = (Folder) source;
for (ILegendItem folderItem : folder.getItems()) {
if (folderItem == target) {
return true;
} else if (folderItem instanceof Folder) {
if (isDescendant(folderItem, target)) {
return true;