6.8.0 RC1

Features

• Support gradients in Cover block.
• Add a breadcrumb bar to support block hierarchy selection.

Enhancements

• Cover block: change the minimum height input step size to one.
• Allow setting a display name for blocks based on their content in the BlockNavigator.
• Hide the gradients panel if an empty set of gradients is explicitly defined.
• Do not transform list items into paragraphs when deleting first list item and list is not empty.
• Replace inline styles with classnames for the gradient palette.
• Preserve list attributes (start, type and reversed) when pasting or converting HTML to blocks. 

Bugs

• Clear local autosaves after successful saves.
• Fix the columns block width overflow issue when using more than two columns.
• Fix the Link Rel input not showing the saved value of the link rel attribute.
• Fix JavaScript errors triggered when using links without href in HTML mode.
• Move the default list styles to the theme editor styles.
• Fix Invalid import statement for deprecated call in the Modal component.
• Fix a small visual glitch in the Publish button.
• Prevent blank page when using the Media Modal Edit Image "back" button.
• Allow the shortcode transform to apply to all the provided shortcode aliases. 
• Fix JavaScript error triggered when using arrows on an empty URLInput.
• Fix extra margins added to Gallery blocks by list editor styles.
• Fix custom button background color not reflected on reload.
• Preserve List block attributes when splitting into multiple lists. 
• Fix checkbox styles when used in metaboxes.
• Make the FontSizePicker style independent from WordPress core styles.
• Fix overlapping controls in the Inline Image formatting toolbar.
• Fix strikethrough formatting when copy/pasting from Google Docs in Safari.
• Allow media upload post processing for all 5xx REST API responses.

Experiments

• Navigation block:
  • Support color customization.
  • Improve the Link edition UI.
• Block Content Areas:
  • Implement a frontend template loader based on the  wp_template CPT.
  • Add a temporary UI to edit wp_template CPT posts.
  • Add a Site title block.

New APIs

• Add VisuallyHidden component.
• Add @wordpress/base-styles package to share the common variables/mixins used by the WordPress packages.
• Add Platform component to allow writing platform (web, mobile) specific logic.
• Add isInvalidDate prop to DatePicker.
• @wordpress/env improvements:
  • Support custom ports.
  • Support using it for themes.
• Add a new experimental React  hook to support colors in blocks.
• Add a new experimental DimentionControl component.

Various

• Storybook:
  • Add a story for the CheckboxControl component.
  • Add a story for the Dashicon component.
  • Add a story for the ColorPalette component.
  • Add a story for the ColorPicker component.
  • Add a story for the ExternalLink component.

Add knobs to the ColorIndicator Story.

• Several other enhancements to existing stories.
• Linting fixes for Storybook config.
• Fix Lint warnings triggered by JSDoc definitions.
• Reorganize e2e tests specs into three folders: editor, experimental and plugin.
• Cleanup skipped e2e tests.
• Add a link to Storybook from the Gutenberg playground.
• Optimize the @wordpress/compose package to support tree-shaking.
• Code Quality:
  • Refactor the Button block edit function to use a functional component.
  • Change the name of the accumulated variables in reduce functions.
  • Remove wrapper around the Table block cells.
• Fix several issues related to Node 12 becoming LTS.
• Add the Block Inspector to the Gutenberg playground.

Documentation

• Enhance the Git workflow documentation.
• Clarify block naming conventions.
• Tweaks and typos: 1, 2.