Working on UI improvement

src/items/Item.h

@@ -2,6 +2,7 @@
 #include <string>
 #include <memory>
 #include <vector>
+#include <functional>
 
 namespace ZL {
 
@@ -28,6 +29,9 @@ namespace ZL {
 		bool hasItem(const std::string& itemId) const;
 		void clear() { items.clear(); }
 		size_t getCount() const { return items.size(); }
+
+		// Called whenever an item is added; receives the item id.
+		std::function<void(const std::string&)> onItemAdded;
 	};
 
 } // namespace ZL