virtual ChildrenList get_selected_children()const=0;
//! Returns the first children selected or an empty handle if none are selected.
virtual ChildrenList::value_type get_selected_child()const=0;
virtual ChildrenList get_selected_children()const=0;
//! Returns the first children selected or an empty handle if none are selected.
virtual ChildrenList::value_type get_selected_child()const=0;