Retro 6.6 Beta 3 Release and Gutenberg Editor Enhancements

The chapter focuses on the release of Retro 6.6 beta 3, emphasizing the importance of testing compatibility with sites, plugins, and themes. It highlights the use of Playground for testing purposes and discusses improvements in the Gutenberg editor, including dynamic accessibility to block features and support for background images and post content blocks. The chapter also touches on the introduction of custom CSS handling, bug fixes, and the implementation of an action extensibility API for data views in WordPress.