@Override
 public boolean select(Viewer viewer, Object parentElement, Object element) {
   if (element instanceof CeylonOutlineNode) {
     CeylonOutlineNode node = (CeylonOutlineNode) element;
     return node.isShared();
   } else if (element instanceof Declaration) {
     Declaration dec = (Declaration) element;
     return dec.isShared();
   } else {
     return true;
   }
 }