feat: Control widget for enum fields (dropdown box)

Change-Id: Id762960d4a9ef6b18a5b35c5528928f32d79d248
diff --git a/test/test_config_ui.py b/test/test_config_ui.py
index 78d83a0..77b5ddd 100644
--- a/test/test_config_ui.py
+++ b/test/test_config_ui.py
@@ -128,3 +128,11 @@
         wdg.listen_change(lambda x, y, z: self._print_cfg())
 
         self.assertTrue(self._run_ui())
+
+    def test_dropdown_widget(self):
+        cfg = self.store.get_config(ExampleConfig)
+        wdg = cfg.ui_create_int_option_dropdown(self.frm)
+        wdg.pack()
+        wdg.listen_change(lambda x, y, z: self._print_cfg())
+
+        self.assertTrue(self._run_ui())