---
fixes:
  - |
    [:bug:`1564543`] ``AVAILABLE_THEMES`` was used to determine whether
    a theme was selectable via the user facing widget, however it was noted
    that sometimes a parent theme is desired for inheritance, and needs to
    be hidden from the widget entirely. ``SELECTABLE_THEMES`` was
    added as a setting that can be used to collect a theme for inheritance,
    but hide it from the user's view.
    See `the settings documentation <https://docs.openstack.org/horizon/latest/configuration/themes.html#inherit-from-an-existing-theme>`__
    for usage specifics.