As part of a [wider redesign](https://github.com/wagtail/wagtail/discussions/7739) of Wagtail’s administration interface, we have replaced the sidebar with a slim, keyboard-friendly version. This re-implementation comes with significant accessibility improvements for keyboard and screen reader users, and will enable us to make navigation between views much snappier in the future. Please have a look at [upgrade considerations](#upgrade-considerations) for more details on differences with the previous version.
* Add a 'remember me' checkbox to the admin sign in form, if unticked (default) the auth session will expire if the browser is closed (Michael Karamuth, Jake Howard)
* Accessibility fixes for Windows high contrast mode; Dashboard icons colour and contrast, help/error/warning blocks for fields and general content, side comment buttons within the page editor, dropdown buttons (Sakshi Uppoor, Shariq Jamil, LB (Ben Johnston), Jason Attwood)
* Pages are refreshed from database on create before passing to hooks. Page aliases get correct `first_published_date` and `last_published_date` (Dan Braghis)
### StreamField ListBlock now returns `ListValue` rather than a list instance
The data type returned as the value of a ListBlock is now a custom class, `ListValue`, rather than a Python `list` object. This change allows it to provide a `bound_blocks` property that exposes the list items as [`BoundBlock` objects](../advanced_topics/boundblocks_and_values) rather than plain values. `ListValue` objects are mutable sequences that behave similarly to lists, and so all code that iterates over them, accesses individual elements, or manipulates them should continue to work. However, code that specifically expects a `list` object (e.g. using `isinstance` or testing for equality against a list) may need to be updated. For example, a unit test that tests the value of a `ListBlock` as follows:
This release upgrades the [django-taggit](https://django-taggit.readthedocs.io/en/latest/) library to 2.x, which introduces one breaking change: the `TaggableManager.set` method now accepts a list of tags as a single argument, rather than a variable number of arguments. Code such as `page.tags.set('red', 'blue')` should be updated to `page.tags.set(['red', 'blue'])`.
The internal (undocumented) class-based view `wagtail.admin.views.generic.DeleteView` has been updated to align with [Django 4.0's `DeleteView` implementation](https://docs.djangoproject.com/en/4.0/releases/4.0/#deleteview-changes), which uses `FormMixin` to handle POST requests. Any custom deletion logic in `delete()` handlers should be moved to `form_valid()`.
`admin/expanding_formset.js` has been renamed to `admin/expanding-formset.js` as part of frontend code clean up work. Check for any customised admin views that are extending expanding formsets, or have overridden template and copied the previous file name used in an import as these may need updating.
The new sidebar largely supports the same customisations as its predecessor, with a few exceptions:
- Top-level menu items should now always provide an `icon_name`, so they can be visually distinguished when the sidebar is collapsed.
-`MenuItem` and its sub-classes no longer supports customizing arbitrary HTML attributes.
-`MenuItem` can no longer be sub-classed to customise its HTML output or load additional JavaScript
For sites relying on those capabilities, we provide a [`WAGTAIL_SLIM_SIDEBAR = False`](../reference/settings/#WAGTAIL_SLIM_SIDEBAR) setting to switch back to the legacy sidebar. The legacy sidebar and this setting will be removed in Wagtail 2.18.
