6.0.0 RC1

Features

• Support choosing a pre-defined layout for the Columns block. 

Enhancements

• Add Snackbar notices support to the widgets screen.
• Add an inner container to the Group block to simplify theme styling.
• Avoid stacking successive MediaPlaceholder errors.
• Adjust the DatePicker margins.
• Update the Tag Cloud block copy when no terms are found.
• Add descriptive text and a link to documentation in embed blocks.
• Improve placeholder text phrasing for media blocks.
• Use classnames for the text alignments in the heading block.
• Make the inserter category icons grayscale.
• A11y: Make the modal overlay scrim darker.

Bug Fixes

• Fix warning messages triggered by the Group block icons.
• Fix horizontal scrollbar on full-wide blocks with nesting.
• A11y: 
  • Re-enable the menu item hover state on small screens.
  • Correct text zoom issue in the Content Structure popover.
• Fix the Popovers position in the widgets screen.
• Fix the behavior of the block toolbars in the widgets screen.
• Fix the editor in IE11 (use the CJS version of react-spring).
• Fix formatting of the validation error messages in the console.
• Fix breakage when the CPT doesn’t support title.

Various

• Document and simplify the multi-entrypoints support in the @wordpress/scripts package. 
• Create sub-registry automatically when using EditorProvider.
• Use classnames utility instead of concatenating classnames in the TabPanel component.
• Remove the default value for the required onRequestClose prop in the Modal component.
• Remove the editor package dependency from the media blocks.
• Fix the playground build script.
• Fix the Github action assigning milestones.
• Fix naming conventions for function containing CLI keyword.
• Fix the Travis build artifacts job to use a full npm install while building.
• Make Calendar block resilient to the editor module not being present.
• Ensure the Snackbar component is only used with a single action button.
• Remove SlotFillProvider and DropZoneProvider from the BlockEditorProvider.
• Add the initial version of the Block Registration RFC.
• Add popoverProps prop to the Dropdown component.
• Update Image Block's image classes with dimensions.
• Support registering custom grouping blocks.
• Fix h1 heading typo so h1 is same size as title.
• Remove the custom class support from the legacy widget block.

Documentation

• Prefer register_post_meta over register_meta.
• Add mention of Figma to the design contributing docs.
• Add supported attribute types for the Blocks API.
• Enhance the Annotations API documentation.
• Tweaks and typos: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11.

Mobile

• Fix multiline Image block captions in iOS.
• Avoid unnecessary div elements in the content of Quote blocks.
• Update the default colors used in the RichText component.
• Fix pasting text on Post Title.
• Unify the web and mobile components hierarchy:
  • BlockPicker and Inserter.
  • BlockToolbar.
  • BlockMobileToolbar.
  • BlockListBlock.
  • BlockList.
• Add native component HTMLTextInput.
• Update the video player to open the URL by browser on Android.
• Re-enable the Video block on Android.