Try: "Focus Mode".

edit-post/components/layout/index.js

@@ -52,12 +52,14 @@ function Layout( {
 	hasActiveMetaboxes,
 	isSaving,
 	isMobileViewport,
+	isFocusMode,
 } ) {
 	const sidebarIsOpened = editorSidebarOpened || pluginSidebarOpened || publishSidebarOpened;
 
 	const className = classnames( 'edit-post-layout', {
 		'is-sidebar-opened': sidebarIsOpened,
 		'has-fixed-toolbar': hasFixedToolbar,
+		'is-focus-mode': isFocusMode,
 	} );
 
 	const publishLandmarkProps = {
@@ -143,6 +145,7 @@ export default compose(
 		metaBoxes: select( 'core/edit-post' ).getMetaBoxes(),
 		hasActiveMetaboxes: select( 'core/edit-post' ).hasMetaBoxes(),
 		isSaving: select( 'core/edit-post' ).isSavingMetaBoxes(),
+		isFocusMode: select( 'core/edit-post' ).isFocusMode(),
 	} ) ),
 	withDispatch( ( dispatch ) => {
 		const { closePublishSidebar, togglePublishSidebar } = dispatch( 'core/edit-post' );

edit-post/hooks/more-menu/focus-mode.js

@@ -0,0 +1,30 @@
+/**
+ * WordPress dependencies
+ */
+import { MenuItem } from '@wordpress/components';
+import { withDispatch, withSelect } from '@wordpress/data';
+import { __ } from '@wordpress/i18n';
+import { compose } from '@wordpress/compose';
+
+function FocusModeMenuItem( { isFocusMode, toggleFocusMode } ) {
+	return (
+		<MenuItem
+			icon={ isFocusMode && 'yes' }
+			onClick={ toggleFocusMode }
+		>
+			{ __( 'Focus Mode' ) }
+		</MenuItem>
+	);
+}
+
+export default compose(
+	withSelect( ( select ) => ( {
+		isFocusMode: select( 'core/edit-post' ).isFocusMode(),
+	} ) ),
+	withDispatch( ( dispatch ) => {
+		const { toggleFocusMode } = dispatch( 'core/edit-post' );
+		return {
+			toggleFocusMode: toggleFocusMode,
+		};
+	} ),
+)( FocusModeMenuItem );

edit-post/hooks/more-menu/index.js

@@ -7,14 +7,26 @@ import { addFilter } from '@wordpress/hooks';
  * Internal dependencies
  */
 import CopyContentMenuItem from './copy-content-menu-item';
+import FocusMode from './focus-mode';
 
-const withCopyContentMenuItem = ( menuItems ) => [
+const withCopyMenuItem = ( menuItems ) => [
 	...menuItems,
 	<CopyContentMenuItem key="copy-content-menu-item" />,
 ];
 
 addFilter(
 	'editPost.MoreMenu.tools',
 	'core/edit-post/more-menu/withCopyContentMenuItem',
-	withCopyContentMenuItem
+	withCopyMenuItem
+);
+
+const withFocusMode = ( menuItems ) => [
+	...menuItems,
+	<FocusMode key="focus-mode" />,
+];
+
+addFilter(
+	'editPost.MoreMenu.tools',
+	'core/edit-post/more-menu/focusMode',
+	withFocusMode
 );

edit-post/store/actions.js

@@ -96,6 +96,17 @@ export function toggleGeneralSidebarEditorPanel( panel ) {
 	};
 }
 
+/**
+ * Returns an action object used in signalling that the user toggles focus mode.
+ *
+ * @return {Object} Action object
+ */
+export function toggleFocusMode() {
+	return {
+		type: 'TOGGLE_FOCUS_MODE',
+	};
+}
+
 /**
  * Returns an action object used to toggle a feature flag.
  *

edit-post/store/reducer.js

@@ -119,6 +119,14 @@ export function publishSidebarActive( state = false, action ) {
 	return state;
 }
 
+export function focusModeActive( state = false, action ) {
+	switch ( action.type ) {
+		case 'TOGGLE_FOCUS_MODE':
+			return ! state;
+	}
+	return state;
+}
+
 const locations = [
 	'normal',
 	'side',
@@ -195,6 +203,7 @@ export default combineReducers( {
 	panel,
 	activeModal,
 	publishSidebarActive,
+	focusModeActive,
 	metaBoxes,
 	isSavingMetaBoxes,
 } );

edit-post/store/selectors.js

@@ -99,6 +99,17 @@ export function isEditorSidebarPanelOpened( state, panel ) {
 	return panels ? !! panels[ panel ] : false;
 }
 
+/**
+ * Returns true if focus mode is enabled.
+ *
+ * @param {Object} state Global application state
+ *
+ * @return {boolean} Whether focus mode is enabled.
+ */
+export function isFocusMode( state ) {
+	return state.focusModeActive;
+}
+
 /**
  * Returns true if a modal is active, or false otherwise.
  *

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

@@ -79,7 +79,6 @@
 	cursor: grab;
 }
 
-
 // Allow Drag & Drop when clicking on the empty area of the mover and the settings menu
 .editor-block-list__layout .editor-block-list__block .editor-block-mover,
 .editor-block-list__layout .editor-block-list__block .editor-block-settings-menu {
@@ -1029,3 +1028,46 @@
 		}
 	}
 }
+
+// When focus mode is engaged, dim down visibility of non-selected blocks
+.editor-block-list__layout .editor-block-list__block:not(.is-selected):not(.is-typing) {
+	.is-focus-mode & {
+		opacity: 0.2;
+	}
+}
+
+.editor-block-list__layout .editor-block-contextual-toolbar,
+.editor-block-settings-menu,
+.editor-block-mover,
+.editor-block-list__block.is-hovered .editor-block-list__block-edit::before,
+.editor-block-list__breadcrumb,
+.editor-post-permalink {
+	.is-focus-mode & {
+		display: none !important;
+		outline: none !important;
+	}
+}
+
+.is-focus-mode .edit-post-header {
+	.edit-post-header-toolbar {
+		> * {
+			visibility: hidden !important;
+		}
+
+		.editor-inserter,
+		.editor-history__undo,
+		.editor-history__redo,
+		.edit-post-header-toolbar__block-toolbar {
+			visibility: visible !important;
+		}
+	}
+	.edit-post-header__settings {
+		> * {
+			visibility: hidden !important;
+		}
+
+		.edit-post-more-menu {
+			visibility: visible !important;
+		}
+	}
+}