Nested blocks: Show the side inserter on empty paragraphs

blocks/api/utils.js

@@ -3,6 +3,11 @@
  */
 import { every, keys, isEqual } from 'lodash';
 
+/**
+ * WordPress dependencies
+ */
+import { applyFilters } from '@wordpress/hooks';
+
 /**
  * Internal dependencies
  */
@@ -25,10 +30,11 @@ export function isUnmodifiedDefaultBlock( block ) {
 	}
 
 	const newDefaultBlock = createBlock( defaultBlockName );
-	const attributeKeys = [
+
+	const attributeKeys = applyFilters( 'blocks.isUnmodifiedDefaultBlock.attributes', [
 		...keys( newDefaultBlock.attributes ),
 		...keys( block.attributes ),
-	];
+	] );
 
 	return every( attributeKeys, key =>
 		isEqual( newDefaultBlock.attributes[ key ], block.attributes[ key ] )

blocks/hooks/layout.js

@@ -1,7 +1,7 @@
 /**
  * External dependencies
  */
-import { assign, compact, get } from 'lodash';
+import { assign, compact, get, without } from 'lodash';
 
 /**
  * WordPress dependencies
@@ -70,6 +70,19 @@ function preserveLayoutAttribute( transformedBlock, blocks ) {
 	return transformedBlock;
 }
 
+/**
+ * Excludes the layout from the list of attributes to check
+ * when determining if a block is unmodified or not.
+ *
+ * @param  {Object} attributeKeys  Attribute keys to check
+ *
+ * @return {Object}                Modified list of attribute keys
+ */
+function excludeLayoutFromUnmodifiedBlockCheck( attributeKeys ) {
+	return without( attributeKeys, 'layout' );
+}
+
 addFilter( 'blocks.registerBlockType', 'core/layout/attribute', addAttribute );
 addFilter( 'blocks.getSaveContent.extraProps', 'core/layout/save-props', addSaveProps );
 addFilter( 'blocks.switchToBlockType.transformedBlock', 'core/layout/preserve-layout', preserveLayoutAttribute );
+addFilter( 'blocks.isUnmodifiedDefaultBlock.attributes', 'core/layout/exclude-layout-attribute-check', excludeLayoutFromUnmodifiedBlockCheck );

blocks/hooks/test/layout.js

@@ -53,4 +53,14 @@ describe( 'layout', () => {
 			expect( transformedBlock.attributes.layout ).toBe( 'wide' );
 		} );
 	} );
+
+	describe( 'excludeLayoutFromUnmodifiedBlockCheck', () => {
+		const excludeLayoutAttribute = applyFilters.bind( null, 'blocks.isUnmodifiedDefaultBlock.attributes' );
+
+		it( 'should exclude the layout attribute', () => {
+			const attributeKeys = excludeLayoutAttribute( [ 'align', 'content', 'layout' ] );
+
+			expect( attributeKeys ).toEqual( [ 'align', 'content' ] );
+		} );
+	} );
 } );