code: public static void convertActivityFromTranslucent(Activity activity) {
          try {
              Method method = Activity.class.getDeclaredMethod("convertFromTranslucent");
              method.setAccessible(true);
              method.invoke(activity);
          } catch (Throwable t) {
          }
      }
docs: Convert a translucent themed Activity
  {@link android.R.attr#windowIsTranslucent} to a fullscreen opaque
  Activity.
  <p>
  Call this whenever the background of a translucent Activity has changed
  to become opaque. Doing so will allow the {@link android.view.Surface} of
  the Activity behind to be released.
  <p>
  This call has no effect on non-translucent activities or on activities
  with the {@link android.R.attr#windowIsFloating} attribute.