+set< RowItemOwner* > RowItemOwner::list_row_item_owners()
+{
+ set< RowItemOwner* > owners;
+ for (const auto &r : *this)
+ owners.insert(r->owner());
+ return owners;
+}
+
+template<class T>
+set< shared_ptr<T> > RowItemOwner::list_by_type()
+{
+ set< shared_ptr<T> > items;
+ for (const auto &r : *this) {
+ shared_ptr<T> p = dynamic_pointer_cast<T>(r);
+ if (p)
+ items.insert(p);
+ }
+
+ return items;
+}
+
+template set< shared_ptr<Trace> > RowItemOwner::list_by_type();
+