[Widgets] Auto expand the last selected widget area when opening the inserter

packages/block-library/src/widget-area/edit/index.js

@@ -1,7 +1,7 @@
 /**
  * WordPress dependencies
  */
-import { useSelect } from '@wordpress/data';
+import { useSelect, useDispatch } from '@wordpress/data';
 import { EntityProvider } from '@wordpress/core-data';
 import { Panel, PanelBody } from '@wordpress/components';
 
@@ -15,14 +15,22 @@ export default function WidgetAreaEdit( {
 	className,
 	attributes: { id, name },
 } ) {
-	const index = useSelect(
-		( select ) => select( 'core/block-editor' ).getBlockIndex( clientId ),
+	const isOpen = useSelect(
+		( select ) =>
+			select( 'core/edit-widgets' ).getIsWidgetAreaOpen( clientId ),
 		[ clientId ]
 	);
+	const { setIsWidgetAreaOpen } = useDispatch( 'core/edit-widgets' );
 
 	return (
 		<Panel className={ className }>
-			<PanelBody title={ name } initialOpen={ index === 0 }>
+			<PanelBody
+				title={ name }
+				opened={ isOpen }
+				onToggle={ ( opened ) => {
+					setIsWidgetAreaOpen( clientId, opened );
+				} }
+			>
 				<EntityProvider
 					kind="root"
 					type="postType"

packages/edit-widgets/src/components/header/index.js

@@ -1,6 +1,7 @@
 /**
  * WordPress dependencies
  */
+import { useSelect, useDispatch } from '@wordpress/data';
 import { __ } from '@wordpress/i18n';
 import { ToolbarItem } from '@wordpress/components';
 import {
@@ -25,6 +26,22 @@ const inserterToggleProps = { isPrimary: true };
 function Header( { isCustomizer } ) {
 	const isLargeViewport = useViewportMatch( 'medium' );
 	const rootClientId = useLastSelectedRootId();
+	const isLastSelectedWidgetAreaOpen = useSelect(
+		( select ) =>
+			select( 'core/edit-widgets' ).getIsWidgetAreaOpen( rootClientId ),
+		[ rootClientId ]
+	);
+	const { setIsWidgetAreaOpen } = useDispatch( 'core/edit-widgets' );
+	const { selectBlock } = useDispatch( 'core/block-editor' );
+
+	function handleInserterOpen( isOpen ) {
+		if ( isOpen && ! isLastSelectedWidgetAreaOpen ) {
+			// Select the last selected block if hasn't already.
+			selectBlock( rootClientId );
+			// Open the last selected widget area when opening the inserter.
+			setIsWidgetAreaOpen( rootClientId, isOpen );
+		}
+	}
 
 	return (
 		<>
@@ -43,6 +60,7 @@ function Header( { isCustomizer } ) {
 									...toolbarItemProps,
 								} }
 								rootClientId={ rootClientId }
+								onToggle={ handleInserterOpen }
 							/>
 						) }
 					</ToolbarItem>

packages/edit-widgets/src/hooks/use-last-selected-root-id.js

@@ -2,7 +2,6 @@
  * WordPress dependencies
  */
 import { useSelect } from '@wordpress/data';
-import { useRef } from '@wordpress/element';
 
 /**
  * Internal dependencies
@@ -18,28 +17,21 @@ const useLastSelectedRootId = () => {
 			POST_TYPE,
 			buildWidgetAreasPostId()
 		);
-		if ( widgetAreasPost ) {
-			return widgetAreasPost?.blocks[ 0 ]?.clientId;
-		}
+		return widgetAreasPost?.blocks[ 0 ]?.clientId;
 	}, [] );
 
-	const lastSelectedRootIdRef = useRef();
-	if ( ! lastSelectedRootIdRef.current && firstRootId ) {
-		lastSelectedRootIdRef.current = firstRootId;
-	}
-
 	const selectedRootId = useSelect( ( select ) => {
 		const { getBlockRootClientId, getBlockSelectionEnd } = select(
 			'core/block-editor'
 		);
-		return getBlockRootClientId( getBlockSelectionEnd() );
+		const blockSelectionEnd = getBlockSelectionEnd();
+		const blockRootClientId = getBlockRootClientId( blockSelectionEnd );
+		// getBlockRootClientId returns an empty string for top-level blocks, in which case just return the block id.
+		return blockRootClientId === '' ? blockSelectionEnd : blockRootClientId;
 	}, [] );
 
-	if ( selectedRootId ) {
-		lastSelectedRootIdRef.current = selectedRootId;
-	}
-
-	return lastSelectedRootIdRef.current;
+	// Fallbacks to the first widget area.
+	return selectedRootId || firstRootId;
 };
 
 export default useLastSelectedRootId;

packages/edit-widgets/src/store/actions.js

@@ -147,3 +147,31 @@ export function setWidgetIdForClientId( clientId, widgetId ) {
 		widgetId,
 	};
 }
+
+/**
+ * Sets the open state of all the widget areas.
+ *
+ * @param  {Object} widgetAreasOpenState The open states of all the widget areas.
+ * @return {Object}                      Action.
+ */
+export function setWidgetAreasOpenState( widgetAreasOpenState ) {
+	return {
+		type: 'SET_WIDGET_AREAS_OPEN_STATE',
+		widgetAreasOpenState,
+	};
+}
+
+/**
+ * Sets the open state of the widget area.
+ *
+ * @param  {string}  clientId   The clientId of the widget area.
+ * @param  {boolean} isOpen     Whether the widget area should be opened.
+ * @return {Object}             Action.
+ */
+export function setIsWidgetAreaOpen( clientId, isOpen ) {
+	return {
+		type: 'SET_IS_WIDGET_AREA_OPEN',
+		clientId,
+		isOpen,
+	};
+}

packages/edit-widgets/src/store/reducer.js

@@ -28,6 +28,33 @@ export function mapping( state, action ) {
 	return state || {};
 }
 
+/**
+ * Controls the open state of the widget areas.
+ *
+ * @param {Object} state   Redux state
+ * @param {Object} action  Redux action
+ * @return {Array}         Updated state
+ */
+export function widgetAreasOpenState( state = {}, action ) {
+	const { type } = action;
+	switch ( type ) {
+		case 'SET_WIDGET_AREAS_OPEN_STATE': {
+			return action.widgetAreasOpenState;
+		}
+		case 'SET_IS_WIDGET_AREA_OPEN': {
+			const { clientId, isOpen } = action;
+			return {
+				...state,
+				[ clientId ]: isOpen,
+			};
+		}
+		default: {
+			return state;
+		}
+	}
+}
+
 export default combineReducers( {
 	mapping,
+	widgetAreasOpenState,
 } );

packages/edit-widgets/src/store/resolvers.js

@@ -7,6 +7,7 @@ import { createBlock } from '@wordpress/blocks';
  * Internal dependencies
  */
 import { resolveWidgetAreas, select, dispatch } from './controls';
+import { setWidgetAreasOpenState } from './actions';
 import {
 	KIND,
 	POST_TYPE,
@@ -61,6 +62,13 @@ export function* getWidgetAreas() {
 		);
 	}
 
+	const widgetAreasOpenState = {};
+	widgetAreaBlocks.forEach( ( widgetAreaBlock, index ) => {
+		// Defaults to open the first widget area.
+		widgetAreasOpenState[ widgetAreaBlock.clientId ] = index === 0;
+	} );
+	yield setWidgetAreasOpenState( widgetAreasOpenState );
+
 	yield persistStubPost( buildWidgetAreasPostId(), widgetAreaBlocks );
 
 	yield {

packages/edit-widgets/src/store/selectors.js

@@ -160,3 +160,15 @@ export const hasResolvedWidgetAreas = createRegistrySelector(
 		return true;
 	}
 );
+
+/**
+ * Gets whether the widget area is opened.
+ *
+ * @param {Array}  state    The open state of the widget areas.
+ * @param {string} clientId The clientId of the widget area.
+ * @return {boolean}        True if the widget area is open.
+ */
+export const getIsWidgetAreaOpen = ( state, clientId ) => {
+	const { widgetAreasOpenState } = state;
+	return !! widgetAreasOpenState[ clientId ];
+};