diff -r 7da74697b7d2 -r 0d165d277562 src/primitives.cpp
--- a/src/primitives.cpp	Wed Mar 14 12:18:52 2018 +0200
+++ b/src/primitives.cpp	Thu Mar 15 10:46:46 2018 +0200
@@ -63,6 +63,9 @@
 	}
 	else
 	{
+		emit layoutAboutToBeChanged();
+		m_primitives.clear();
+
 		while (not primitivesFile.atEnd())
 		{
 			QString line = primitivesFile.readLine().simplified();
@@ -78,6 +81,7 @@
 		}
 
 		populateCategories();
+		emit layoutChanged();
 		print(tr("%1 primitives loaded.") + "\n", countof(m_primitives));
 	}
 }