minor fix

lib/theme/themes.dart

@@ -9,6 +9,9 @@ class Themes {
   static final darkTheme = ThemeData(
     brightness: Brightness.dark,
     accentColor: _accentColor,
+    // canvas color is used as background for the drawer and popups
+    // when using a popup menu on a dialog, lighten the background via `PopupMenuTheme`
+    canvasColor: Colors.grey[850],
     scaffoldBackgroundColor: Colors.grey.shade900,
     dialogBackgroundColor: Colors.grey[850],
     toggleableActiveColor: _accentColor,

lib/widgets/dialogs/video_stream_selection_dialog.dart

@@ -167,6 +167,10 @@ class _VideoStreamSelectionDialogState extends State<VideoStreamSelectionDialog>
           value: current,
           onChanged: streams.length > 1 ? (newValue) => setState(() => setter(newValue)) : null,
           isExpanded: true,
+          // use a different shade to avoid having the same background
+          // on the dialog (using the theme `dialogBackgroundColor`)
+          // and on the dropdown (using the theme `canvasColor`)
+          dropdownColor: Colors.grey.shade800,
         ),
       ),
     ];