diff --git a/gemviz/mainwindow.py b/gemviz/mainwindow.py
index e7d3fcc..15276d1 100644
--- a/gemviz/mainwindow.py
+++ b/gemviz/mainwindow.py
@@ -1,3 +1,9 @@
+"""
+gemviz main window
+"""
+
+# TODO: remove testing URLs before production
+
 import logging
 
 from PyQt5 import QtCore
@@ -6,7 +12,6 @@
 from . import APP_TITLE
 from . import tapi
 from . import utils
-# TODO: remove testing URLs before production
 from .tiledserverdialog import LOCALHOST_URL
 from .tiledserverdialog import TESTING_URL
 from .tiledserverdialog import TILED_SERVER_SETTINGS_KEY