+ virtual std::string state_id() const = 0;
+ /* for now, we always return properties in string form.
+ */
+ std::string gui_property (const std::string& property_name) const;
+
+ template<typename T> void set_gui_property (const std::string& property_name, const T& value) {
+ std::stringstream s;
+ s << value;
+ property_hashtable.erase(property_name);
+ property_hashtable.emplace(property_name, s.str());
+ gui_object_state().set_property<T> (state_id(), property_name, value);
+ }
+
+ void cleanup_gui_properties () {
+ /* remove related property node from the GUI state */
+ gui_object_state().remove_node (state_id());
+ property_hashtable.clear ();
+ }
+
+ bool marked_for_display () const;
+ virtual bool set_marked_for_display (bool);
+
+ static GUIObjectState& gui_object_state();
+ void clear_property_cache() { property_hashtable.clear(); }
+