diff -r e1ced2523cad -r 008989bc7d6e src/model.h
--- a/src/model.h	Tue Nov 02 15:43:57 2021 +0200
+++ b/src/model.h	Tue Mar 01 17:00:19 2022 +0200
@@ -70,7 +70,7 @@
 	void makeUnofficial();
 Q_SIGNALS:
 	void objectAdded(ldraw::id_t id, int position);
-	void objectModified(ldraw::id_t id, int position);
+	void objectStateChanged(int position, const QByteArray& stateBefore, const QByteArray& stateAfter);
 private:
 	using ModelObjectPointer = std::unique_ptr<ldraw::Object>;
 	template<typename T, typename... Args>
@@ -155,7 +155,7 @@
 }
 
 template<typename T, typename... Args>
-ldraw::Id<T> Model::append(Args&&... args)
+T* Model::append(Args&&... args)
 {
 	const int position = static_cast<int>(this->body.size());
 	Q_EMIT beginInsertRows({}, position, position);
@@ -169,7 +169,7 @@
 }
 
 template<typename T, typename... Args>
-ldraw::Id<T> Model::insert(const std::size_t position, Args&&... args)
+T* Model::insert(const std::size_t position, Args&&... args)
 {
 	Q_EMIT beginInsertRows({}, position, position);
 	this->body.insert(std::begin(this->body) + position, std::make_unique<T>(args...));