Use different method to swap show/hide notification menu, hoping to keep to two rows on devices with menu buttons.  Didn't work, then forced the issue by rearranging order.
Keep track of actual number of widgets, since AppWidgetManager.getAppWidgetIds() returns defunct IDs. Unfortunately, the only workaround for existing widgets from 8.1.0 is to remove all widgets to reset count.  Main window then disallows closing if there are any widgets.
Make Service closeable/uncloseable based on AppWidgetProvider's onEnabled()/onDisabled().