diff -r 7c27cda03747 -r 97df974b5ed5 src/modeleditcontext.cpp
--- a/src/modeleditcontext.cpp	Fri Mar 06 23:45:44 2020 +0200
+++ b/src/modeleditcontext.cpp	Mon Mar 09 14:21:54 2020 +0200
@@ -19,15 +19,15 @@
 #include "modeleditcontext.h"
 
 Model::EditContext::EditContext(Model& model) :
-	model{model}
+	storedModel{model}
 {
 }
 
-ldraw::Id Model::EditContext::append(std::unique_ptr<ldraw::Object>&& object)
+ldraw::id_t Model::EditContext::append(std::unique_ptr<ldraw::Object>&& object)
 {
-	const ldraw::Id id = object->id;
-	this->model.objectsById[id] = object.get();
-	this->model.append(std::move(object));
+	const ldraw::id_t id = object->id;
+	this->model().objectsById[id] = object.get();
+	this->model().append(std::move(object));
 	return id;
 }
 
@@ -39,12 +39,32 @@
 	object->setProperty(property, value);
 }
 
-void Model::EditContext::invertObject(ldraw::Id id)
+void Model::EditContext::invertObject(ldraw::id_t id)
 {
-	auto it = this->model.objectsById.find(id);
-	if (it != this->model.objectsById.end())
+	auto it = this->model().objectsById.find(id);
+	if (it != this->model().objectsById.end())
 	{
 		ldraw::Object* object = it->second;
 		object->invert();
 	}
 }
+
+Model& Model::EditContext::model()
+{
+	return this->storedModel;
+}
+
+auto ldraw::splitQuadrilateral(
+	Model::EditContext& editor,
+	ldraw::quadrilateralid_t quadrilateral_id,
+	ldraw::QuadrilateralSplit splitType
+) -> std::optional<std::pair<ldraw::triangleid_t, ldraw::triangleid_t>>
+{
+	std::optional<std::pair<ldraw::triangleid_t, ldraw::triangleid_t>> result;
+	const ldraw::Quadrilateral* quadrilateral = editor.model().get(quadrilateral_id);
+	if (quadrilateral != nullptr)
+	{
+
+	}
+	return result;
+}