diff --git a/poor_mans_visualisation.py b/poor_mans_visualisation.py
index 88cf736..bd7110c 100755
--- a/poor_mans_visualisation.py
+++ b/poor_mans_visualisation.py
@@ -236,6 +236,9 @@ class MainWindow(QtWidgets.QMainWindow):
 		megastyler = self.styling_annotators[-1]
 		assert megastyler.annotator == MegaStyler
 		msann = self.annot_topo.annotations[megastyler]
+		# These two dictionaries are used from outside, so that QGraphicsItems
+		# can resolve graph relations (e.g. to draw the line between the
+		# correct Vertices)
 		self.graphicsitems: dict[VertexID, QGraphicsItem] = dict()
 		self.topologyitems: dict[QGraphicsItem, VertexID|Edge] = dict()
 		for vtxid, style in msann.for_vertex.items():