diff -r 40e2940605a3 -r 4bec0525ef1b src/ui/polygonobjecteditor.cpp
--- a/src/ui/polygonobjecteditor.cpp	Wed Mar 18 17:11:23 2020 +0200
+++ b/src/ui/polygonobjecteditor.cpp	Thu Mar 19 21:06:06 2020 +0200
@@ -1,8 +1,11 @@
 #include <QVBoxLayout>
 #include <QSplitter>
 #include "model.h"
+#include "modeleditcontext.h"
 #include "widgets/vec3editor.h"
-#include "polygonobjecteditor.h"
+#include "ui/polygonobjecteditor.h"
+
+constexpr char COLUMN_PROPERTY[] = "_ldforge_column";
 
 PolygonObjectEditor::PolygonObjectEditor(Model* model, ldraw::id_t id, QWidget* parent) :
 	QWidget{parent},
@@ -10,10 +13,13 @@
 	storedObjectId{ldraw::NULL_ID.value}
 {
 	this->setLayout(new QVBoxLayout{this});
-	for (std::optional<Vec3Editor>& editorPointer : this->vec3Editors)
+	for (int i = 0; i < countof(this->vec3Editors); i += 1)
 	{
+		std::optional<Vec3Editor>& editorPointer = this->vec3Editors[i];
 		editorPointer.emplace(glm::vec3{}, this);
+		editorPointer->setProperty(COLUMN_PROPERTY, QVariant::fromValue(i));
 		this->layout()->addWidget(&*editorPointer);
+		connect(&*editorPointer, &Vec3Editor::valueChanged, this, &PolygonObjectEditor::vectorChanged);
 	}
 	this->layout()->addWidget(new QSplitter{Qt::Vertical, this});
 	this->setObjectId(id);
@@ -35,6 +41,17 @@
 	this->updateNumRows();
 }
 
+void PolygonObjectEditor::vectorChanged(const glm::vec3& value)
+{
+	bool ok;
+	const int num = sender()->property(COLUMN_PROPERTY).toInt(&ok);
+	if (ok and num >= 0 and num < countof(this->vec3Editors))
+	{
+		Model::EditContext editor = this->model->edit();
+		editor.setObjectPoint(this->objectId(), num, value);
+	}
+}
+
 void PolygonObjectEditor::updateNumRows()
 {
 	const ldraw::Object* object = model->get(this->storedObjectId);
@@ -42,6 +59,7 @@
 	for (int i = 0; i < countof(this->vec3Editors); i += 1)
 	{
 		Vec3Editor& editor = *this->vec3Editors[i];
+		QSignalBlocker blocker{&editor};
 		if (i < numPoints)
 		{
 			editor.setVisible(true);