+void Layout::add_signal(Signal &s)
+{
+ if(signals.insert(&s).second)
+ signal_signal_added.emit(s);
+}
+
+Signal *Layout::pick_signal(const Vector &start, const Vector &ray)
+{
+ return pick(signals, start, ray);
+}
+
+void Layout::remove_signal(Signal &s)
+{
+ if(signals.erase(&s))
+ signal_signal_removed.emit(s);
+}
+
+Object *Layout::pick_object(const Vector &start, const Vector &ray)
+{
+ if(Object *obj = pick_track(start, ray))
+ return obj;
+ else if((obj = pick_signal(start, ray)))
+ return obj;
+ return 0;
+}
+
+template<typename T>
+T *Layout::pick(const set<T *> &objs, const Vector &start, const Vector &ray)
+{
+ for(typename set<T *>::const_iterator i=objs.begin(); i!=objs.end(); ++i)
+ if((*i)->collide_ray(start, ray))
+ return *i;
+
+ return 0;
+}
+