diff -r 68443f5be176 -r 44679e468ba9 src/objecttypes/modelobject.h
--- a/src/objecttypes/modelobject.h	Sat Oct 05 23:47:03 2019 +0300
+++ b/src/objecttypes/modelobject.h	Sun Nov 03 12:17:41 2019 +0200
@@ -11,6 +11,7 @@
 	enum class Property;
 	class BaseObject;
 	class ColoredBaseObject;
+	class Empty;
 }
 
 enum class modelobjects::Property
@@ -27,6 +28,7 @@
 	Transformation,
 	ReferenceName,
 	IsInverted,
+	ErrorMessage
 };
 
 class modelobjects::BaseObject
@@ -63,6 +65,11 @@
 	Color color_index = colors::main;
 };
 
+class modelobjects::Empty : public BaseObject
+{
+	QString textRepresentation() const override;
+};
+
 namespace modelobjects
 {
 	using Id = std::remove_const_t<decltype(BaseObject::id)>;