Add reusable BlockPopover and BlockPopoverInbetween components, remove default block appender button for empty paragraphs

packages/base-styles/_z-index.scss

@@ -123,10 +123,7 @@ $z-layers: (
 	".edit-site-navigation-panel__preview": 32,
 
 	// Above the block list and the header.
-	".block-editor-block-list__block-popover": 31,
-
-	// Under the block popover (block toolbar).
-	".block-editor-block-list__insertion-point-popover": 28,
+	".block-editor-block-popover": 31,
 
 	// Show snackbars above everything (similar to popovers)
 	".components-snackbar-list": 100000,

packages/block-editor/src/components/block-popover/README.md

@@ -0,0 +1,41 @@
+# BlockPopover and BlockPopoverInbetween
+
+These two components allow rendering editor UI by the block (in a popover) but outside the canvas. This is important to avoid messing with the style and layout of the block list.
+
+For example, it's used to render the contextual block toolbar and the in-between block inserter.
+
+## BlockPopover
+
+### Props
+
+#### clientId
+
+The client ID of the block representing the top position of the popover.
+
+-   Type: `String`
+-   Required: Yes
+
+#### bottomClientId
+
+The client ID of the block representing the bottom position of the popover.
+
+-   Type: `String`
+-   Required: No
+
+## BlockPopoverInbetween
+
+### Props
+
+#### previousClientId
+
+The client ID of the block before the popover.
+
+-   Type: `String`
+-   Required: Yes
+
+#### nextClientId
+
+The client ID of the block after the popover.
+
+-   Type: `String`
+-   Required: Yes

packages/block-editor/src/components/block-popover/inbetween.js

@@ -0,0 +1,180 @@
+/**
+ * External dependencies
+ */
+import classnames from 'classnames';
+
+/**
+ * WordPress dependencies
+ */
+import { useSelect } from '@wordpress/data';
+import { useCallback, useMemo, createContext } from '@wordpress/element';
+import { Popover } from '@wordpress/components';
+import { isRTL } from '@wordpress/i18n';
+
+/**
+ * Internal dependencies
+ */
+import { store as blockEditorStore } from '../../store';
+import { __unstableUseBlockElement as useBlockElement } from '../block-list/use-block-props/use-block-refs';
+import usePopoverScroll from './use-popover-scroll';
+
+export const InsertionPointOpenRef = createContext();
+
+function BlockPopoverInbetween( {
+	previousClientId,
+	nextClientId,
+	children,
+	__unstablePopoverSlot,
+	__unstableContentRef,
+	...props
+} ) {
+	const { orientation, rootClientId } = useSelect(
+		( select ) => {
+			const { getBlockListSettings, getBlockRootClientId } = select(
+				blockEditorStore
+			);
+
+			const _rootClientId = getBlockRootClientId( previousClientId );
+			return {
+				orientation:
+					getBlockListSettings( _rootClientId )?.orientation ||
+					'vertical',
+				rootClientId: _rootClientId,
+			};
+		},
+		[ previousClientId ]
+	);
+	const previousElement = useBlockElement( previousClientId );
+	const nextElement = useBlockElement( nextClientId );
+	const isVertical = orientation === 'vertical';
+	const style = useMemo( () => {
+		if ( ! previousElement && ! nextElement ) {
+			return {};
+		}
+
+		const previousRect = previousElement
+			? previousElement.getBoundingClientRect()
+			: null;
+		const nextRect = nextElement
+			? nextElement.getBoundingClientRect()
+			: null;
+
+		if ( isVertical ) {
+			return {
+				width: previousElement
+					? previousElement.offsetWidth
+					: nextElement.offsetWidth,
+				height:
+					nextRect && previousRect
+						? nextRect.top - previousRect.bottom
+						: 0,
+			};
+		}
+
+		let width = 0;
+		if ( previousRect && nextRect ) {
+			width = isRTL()
+				? previousRect.left - nextRect.right
+				: nextRect.left - previousRect.right;
+		}
+
+		return {
+			width,
+			height: previousElement
+				? previousElement.offsetHeight
+				: nextElement.offsetHeight,
+		};
+	}, [ previousElement, nextElement, isVertical ] );
+
+	const getAnchorRect = useCallback( () => {
+		if ( ! previousElement && ! nextElement ) {
+			return {};
+		}
+
+		const { ownerDocument } = previousElement || nextElement;
+
+		const previousRect = previousElement
+			? previousElement.getBoundingClientRect()
+			: null;
+		const nextRect = nextElement
+			? nextElement.getBoundingClientRect()
+			: null;
+
+		if ( isVertical ) {
+			if ( isRTL() ) {
+				return {
+					top: previousRect ? previousRect.bottom : nextRect.top,
+					left: previousRect ? previousRect.right : nextRect.right,
+					right: previousRect ? previousRect.left : nextRect.left,
+					bottom: nextRect ? nextRect.top : previousRect.bottom,
+					ownerDocument,
+				};
+			}
+
+			return {
+				top: previousRect ? previousRect.bottom : nextRect.top,
+				left: previousRect ? previousRect.left : nextRect.left,
+				right: previousRect ? previousRect.right : nextRect.right,
+				bottom: nextRect ? nextRect.top : previousRect.bottom,
+				ownerDocument,
+			};
+		}
+
+		if ( isRTL() ) {
+			return {
+				top: previousRect ? previousRect.top : nextRect.top,
+				left: previousRect ? previousRect.left : nextRect.right,
+				right: nextRect ? nextRect.right : previousRect.left,
+				bottom: previousRect ? previousRect.bottom : nextRect.bottom,
+				ownerDocument,
+			};
+		}
+
+		return {
+			top: previousRect ? previousRect.top : nextRect.top,
+			left: previousRect ? previousRect.right : nextRect.left,
+			right: nextRect ? nextRect.left : previousRect.right,
+			bottom: previousRect ? previousRect.bottom : nextRect.bottom,
+			ownerDocument,
+		};
+	}, [ previousElement, nextElement ] );
+
+	const popoverScrollRef = usePopoverScroll( __unstableContentRef );
+
+	if ( ! previousElement || ! nextElement ) {
+		return null;
+	}
+
+	/* eslint-disable jsx-a11y/no-static-element-interactions, jsx-a11y/click-events-have-key-events */
+	// While ideally it would be enough to capture the
+	// bubbling focus event from the Inserter, due to the
+	// characteristics of click focusing of `button`s in
+	// Firefox and Safari, it is not reliable.
+	//
+	// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#Clicking_and_focus
+	return (
+		<Popover
+			ref={ popoverScrollRef }
+			noArrow
+			animate={ false }
+			getAnchorRect={ getAnchorRect }
+			focusOnMount={ false }
+			// Render in the old slot if needed for backward compatibility,
+			// otherwise render in place (not in the the default popover slot).
+			__unstableSlotName={ __unstablePopoverSlot || null }
+			// Forces a remount of the popover when its position changes
+			// This makes sure the popover doesn't animate from its previous position.
+			key={ nextClientId + '--' + rootClientId }
+			{ ...props }
+			className={ classnames(
+				'block-editor-block-popover',
+				props.className
+			) }
+		>
+			<div style={ style }>{ children }</div>
+		</Popover>
+	);
+	/* eslint-enable jsx-a11y/no-static-element-interactions, jsx-a11y/click-events-have-key-events */
+}
+
+export default BlockPopoverInbetween;

packages/block-editor/src/components/block-popover/index.js

@@ -0,0 +1,73 @@
+/**
+ * External dependencies
+ */
+import classnames from 'classnames';
+
+/**
+ * WordPress dependencies
+ */
+import { Popover } from '@wordpress/components';
+import { getScrollContainer } from '@wordpress/dom';
+
+/**
+ * Internal dependencies
+ */
+import { __unstableUseBlockElement as useBlockElement } from '../block-list/use-block-props/use-block-refs';
+import usePopoverScroll from './use-popover-scroll';
+
+export default function BlockPopover( {
+	clientId,
+	bottomClientId,
+	children,
+	__unstablePopoverSlot,
+	__unstableContentRef,
+	...props
+} ) {
+	const selectedElement = useBlockElement( clientId );
+	const lastSelectedElement = useBlockElement( bottomClientId ?? clientId );
+	const popoverScrollRef = usePopoverScroll( __unstableContentRef );
+
+	if ( ! selectedElement || ( bottomClientId && ! lastSelectedElement ) ) {
+		return null;
+	}
+
+	const anchorRef = {
+		top: selectedElement,
+		bottom: lastSelectedElement,
+	};
+
+	const { ownerDocument } = selectedElement;
+	const stickyBoundaryElement =
+		ownerDocument.defaultView.frameElement ||
+		getScrollContainer( selectedElement ) ||
+		ownerDocument.body;
+
+	return (
+		<Popover
+			ref={ popoverScrollRef }
+			noArrow
+			animate={ false }
+			position="top right left"
+			focusOnMount={ false }
+			anchorRef={ anchorRef }
+			__unstableStickyBoundaryElement={ stickyBoundaryElement }
+			// Render in the old slot if needed for backward compatibility,
+			// otherwise render in place (not in the the default popover slot).
+			__unstableSlotName={ __unstablePopoverSlot || null }
+			__unstableBoundaryParent
+			// Observe movement for block animations (especially horizontal).
+			__unstableObserveElement={ selectedElement }
+			shouldAnchorIncludePadding
+			// Used to safeguard sticky position behavior against cases where it would permanently
+			// obscure specific sections of a block.
+			__unstableEditorCanvasWrapper={ __unstableContentRef?.current }
+			{ ...props }
+			className={ classnames(
+				'block-editor-block-popover',
+				props.className
+			) }
+		>
+			{ children }
+		</Popover>
+	);
+}

packages/block-editor/src/components/block-popover/style.scss

@@ -0,0 +1,24 @@
+
+.components-popover.block-editor-block-popover {
+	z-index: z-index(".block-editor-block-popover");
+	position: absolute;
+
+	.components-popover__content {
+		margin: 0 !important;
+		min-width: auto;
+		width: max-content;
+		background: none;
+		border: none;
+		box-shadow: none;
+		overflow-y: visible;
+
+		// Allow clicking through the toolbar holder.
+		pointer-events: none;
+
+		// Position the block toolbar.
+		> * {
+			pointer-events: all;
+		}
+	}
+}
+

packages/block-editor/src/components/block-tools/use-popover-scroll.js → packages/block-editor/src/components/block-popover/use-popover-scroll.js

@@ -10,7 +10,7 @@ import { useRefEffect } from '@wordpress/compose';
  *
  * @param {Object} scrollableRef
  */
-export function usePopoverScroll( scrollableRef ) {
+function usePopoverScroll( scrollableRef ) {
 	return useRefEffect(
 		( node ) => {
 			if ( ! scrollableRef ) {
@@ -32,3 +32,5 @@ export function usePopoverScroll( scrollableRef ) {
 		[ scrollableRef ]
 	);
 }
+
+export default usePopoverScroll;

packages/block-editor/src/components/block-tools/back-compat.js

@@ -9,7 +9,7 @@ import deprecated from '@wordpress/deprecated';
  * Internal dependencies
  */
 import InsertionPoint, { InsertionPointOpenRef } from './insertion-point';
-import BlockPopover from './block-popover';
+import BlockPopover from './selected-block-popover';
 
 export default function BlockToolsBackCompat( { children } ) {
 	const openRef = useContext( InsertionPointOpenRef );

packages/block-editor/src/components/block-tools/block-selection-button.js

@@ -38,6 +38,7 @@ import BlockIcon from '../block-icon';
 import { store as blockEditorStore } from '../../store';
 import BlockDraggable from '../block-draggable';
 import useBlockDisplayInformation from '../use-block-display-information';
+import { __unstableUseBlockElement as useBlockElement } from '../block-list/use-block-props/use-block-refs';
 
 /**
  * Block selection button component, displaying the label of the block. If the block
@@ -49,7 +50,7 @@ import useBlockDisplayInformation from '../use-block-display-information';
  *
  * @return {WPComponent} The component to be rendered.
  */
-function BlockSelectionButton( { clientId, rootClientId, blockElement } ) {
+function BlockSelectionButton( { clientId, rootClientId } ) {
 	const blockInformation = useBlockDisplayInformation( clientId );
 	const selected = useSelect(
 		( select ) => {
@@ -90,6 +91,7 @@ function BlockSelectionButton( { clientId, rootClientId, blockElement } ) {
 
 		speak( label );
 	}, [ label ] );
+	const blockElement = useBlockElement( clientId );
 
 	const {
 		hasBlockMovingClientId,