chrome-devtools-frontend/front_end/panels/elements/StylesSidebarPane.ts

Chrome DevTools UI

// Copyright 2021 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/*
 * Copyright (C) 2007 Apple Inc.  All rights reserved.
 * Copyright (C) 2009 Joseph Pecoraro
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import * as Common from '../../core/common/common.js';
import * as Host from '../../core/host/host.js';
import * as i18n from '../../core/i18n/i18n.js';
import * as Platform from '../../core/platform/platform.js';
import * as Root from '../../core/root/root.js';
import * as SDK from '../../core/sdk/sdk.js';
import * as Protocol from '../../generated/protocol.js';
import * as Bindings from '../../models/bindings/bindings.js';
import * as TextUtils from '../../models/text_utils/text_utils.js';
import * as IconButton from '../../ui/components/icon_button/icon_button.js';
import * as InlineEditor from '../../ui/legacy/components/inline_editor/inline_editor.js';
import * as Components from '../../ui/legacy/components/utils/utils.js';
import * as UI from '../../ui/legacy/legacy.js';

import {FontEditorSectionManager} from './ColorSwatchPopoverIcon.js';
import * as ElementsComponents from './components/components.js';
import type {ComputedStyleChangedEvent} from './ComputedStyleModel.js';
import {ComputedStyleModel} from './ComputedStyleModel.js';
import {linkifyDeferredNodeReference} from './DOMLinkifier.js';
import {ElementsPanel} from './ElementsPanel.js';
import {ElementsSidebarPane} from './ElementsSidebarPane.js';
import {ImagePreviewPopover} from './ImagePreviewPopover.js';
import {StyleEditorWidget} from './StyleEditorWidget.js';
import {StylePropertyHighlighter} from './StylePropertyHighlighter.js';
import stylesSectionTreeStyles from './stylesSectionTree.css.js';
import stylesSidebarPaneStyles from './stylesSidebarPane.css.js';

import type {Context} from './StylePropertyTreeElement.js';
import {StylePropertyTreeElement} from './StylePropertyTreeElement.js';

const UIStrings = {
  /**
  *@description No matches element text content in Styles Sidebar Pane of the Elements panel
  */
  noMatchingSelectorOrStyle: 'No matching selector or style',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  invalidPropertyValue: 'Invalid property value',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  unknownPropertyName: 'Unknown property name',
  /**
  *@description Text to filter result items
  */
  filter: 'Filter',
  /**
  *@description ARIA accessible name in Styles Sidebar Pane of the Elements panel
  */
  filterStyles: 'Filter Styles',
  /**
  *@description Separator element text content in Styles Sidebar Pane of the Elements panel
  *@example {scrollbar-corner} PH1
  */
  pseudoSElement: 'Pseudo ::{PH1} element',
  /**
  *@description Text of a DOM element in Styles Sidebar Pane of the Elements panel
  */
  inheritedFroms: 'Inherited from ',
  /**
  *@description Tooltip text that appears when hovering over the largeicon add button in the Styles Sidebar Pane of the Elements panel
  */
  insertStyleRuleBelow: 'Insert Style Rule Below',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  constructedStylesheet: 'constructed stylesheet',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  userAgentStylesheet: 'user agent stylesheet',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  injectedStylesheet: 'injected stylesheet',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  viaInspector: 'via inspector',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  */
  styleAttribute: '`style` attribute',
  /**
  *@description Text in Styles Sidebar Pane of the Elements panel
  *@example {html} PH1
  */
  sattributesStyle: '{PH1}[Attributes Style]',
  /**
  *@description Show all button text content in Styles Sidebar Pane of the Elements panel
  *@example {3} PH1
  */
  showAllPropertiesSMore: 'Show All Properties ({PH1} more)',
  /**
  *@description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
  */
  copySelector: 'Copy `selector`',
  /**
  *@description A context menu item in Styles panel to copy CSS rule
  */
  copyRule: 'Copy rule',
  /**
  *@description A context menu item in Styles panel to copy all CSS declarations
  */
  copyAllDeclarations: 'Copy all declarations',
  /**
  *@description Title of  in styles sidebar pane of the elements panel
  *@example {Ctrl} PH1
  */
  incrementdecrementWithMousewheelOne:
      'Increment/decrement with mousewheel or up/down keys. {PH1}: R ±1, Shift: G ±1, Alt: B ±1',
  /**
  *@description Title of  in styles sidebar pane of the elements panel
  *@example {Ctrl} PH1
  */
  incrementdecrementWithMousewheelHundred:
      'Increment/decrement with mousewheel or up/down keys. {PH1}: ±100, Shift: ±10, Alt: ±0.1',
  /**
  *@description Announcement string for invalid properties.
  *@example {Invalid property value} PH1
  *@example {font-size} PH2
  *@example {invalidValue} PH3
  */
  invalidString: '{PH1}, property name: {PH2}, property value: {PH3}',
  /**
  *@description Tooltip text that appears when hovering over the largeicon add button in the Styles Sidebar Pane of the Elements panel
  */
  newStyleRule: 'New Style Rule',
  /**
  *@description Text that is announced by the screen reader when the user focuses on an input field for entering the name of a CSS property in the Styles panel
  */
  cssPropertyName: '`CSS` property name',
  /**
  *@description Text that is announced by the screen reader when the user focuses on an input field for entering the value of a CSS property in the Styles panel
  */
  cssPropertyValue: '`CSS` property value',
  /**
  *@description Text that is announced by the screen reader when the user focuses on an input field for editing the name of a CSS selector in the Styles panel
  */
  cssSelector: '`CSS` selector',
};

const str_ = i18n.i18n.registerUIStrings('panels/elements/StylesSidebarPane.ts', UIStrings);
const i18nString = i18n.i18n.getLocalizedString.bind(undefined, str_);

// Highlightable properties are those that can be hovered in the sidebar to trigger a specific
// highlighting mode on the current element.
const HIGHLIGHTABLE_PROPERTIES = [
  {mode: 'padding', properties: ['padding']},
  {mode: 'border', properties: ['border']},
  {mode: 'margin', properties: ['margin']},
  {mode: 'gap', properties: ['gap', 'grid-gap']},
  {mode: 'column-gap', properties: ['column-gap', 'grid-column-gap']},
  {mode: 'row-gap', properties: ['row-gap', 'grid-row-gap']},
  {mode: 'grid-template-columns', properties: ['grid-template-columns']},
  {mode: 'grid-template-rows', properties: ['grid-template-rows']},
  {mode: 'grid-template-areas', properties: ['grid-areas']},
  {mode: 'justify-content', properties: ['justify-content']},
  {mode: 'align-content', properties: ['align-content']},
  {mode: 'align-items', properties: ['align-items']},
  {mode: 'flexibility', properties: ['flex', 'flex-basis', 'flex-grow', 'flex-shrink']},
];

// TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
// eslint-disable-next-line @typescript-eslint/naming-convention
let _stylesSidebarPaneInstance: StylesSidebarPane;

// TODO(crbug.com/1172300) This workaround is needed to keep the linter happy.
// Otherwise it complains about: Unknown word CssSyntaxError
const STYLE_TAG = '<' +
    'style>';

export class StylesSidebarPane extends Common.ObjectWrapper.eventMixin<EventTypes, typeof ElementsSidebarPane>(
    ElementsSidebarPane) {
  private currentToolbarPane: UI.Widget.Widget|null;
  private animatedToolbarPane: UI.Widget.Widget|null;
  private pendingWidget: UI.Widget.Widget|null;
  private pendingWidgetToggle: UI.Toolbar.ToolbarToggle|null;
  private toolbar: UI.Toolbar.Toolbar|null;
  private toolbarPaneElement: HTMLElement;
  private noMatchesElement: HTMLElement;
  private sectionsContainer: HTMLElement;
  sectionByElement: WeakMap<Node, StylePropertiesSection>;
  private readonly swatchPopoverHelperInternal: InlineEditor.SwatchPopoverHelper.SwatchPopoverHelper;
  readonly linkifier: Components.Linkifier.Linkifier;
  private readonly decorator: StylePropertyHighlighter;
  private lastRevealedProperty: SDK.CSSProperty.CSSProperty|null;
  private userOperation: boolean;
  isEditingStyle: boolean;
  private filterRegexInternal: RegExp|null;
  private isActivePropertyHighlighted: boolean;
  private initialUpdateCompleted: boolean;
  hasMatchedStyles: boolean;
  private sectionBlocks: SectionBlock[];
  private idleCallbackManager: IdleCallbackManager|null;
  private needsForceUpdate: boolean;
  private readonly resizeThrottler: Common.Throttler.Throttler;
  private readonly imagePreviewPopover: ImagePreviewPopover;
  activeCSSAngle: InlineEditor.CSSAngle.CSSAngle|null;

  static instance(): StylesSidebarPane {
    if (!_stylesSidebarPaneInstance) {
      _stylesSidebarPaneInstance = new StylesSidebarPane();
    }
    return _stylesSidebarPaneInstance;
  }

  private constructor() {
    super(true /* delegatesFocus */);
    this.setMinimumSize(96, 26);
    this.registerCSSFiles([stylesSidebarPaneStyles]);
    Common.Settings.Settings.instance().moduleSetting('colorFormat').addChangeListener(this.update.bind(this));
    Common.Settings.Settings.instance().moduleSetting('textEditorIndent').addChangeListener(this.update.bind(this));

    this.currentToolbarPane = null;
    this.animatedToolbarPane = null;
    this.pendingWidget = null;
    this.pendingWidgetToggle = null;
    this.toolbar = null;
    this.toolbarPaneElement = this.createStylesSidebarToolbar();
    this.computedStyleModelInternal = new ComputedStyleModel();

    this.noMatchesElement = this.contentElement.createChild('div', 'gray-info-message hidden');
    this.noMatchesElement.textContent = i18nString(UIStrings.noMatchingSelectorOrStyle);

    this.sectionsContainer = this.contentElement.createChild('div');
    UI.ARIAUtils.markAsList(this.sectionsContainer);
    this.sectionsContainer.addEventListener('keydown', this.sectionsContainerKeyDown.bind(this), false);
    this.sectionsContainer.addEventListener('focusin', this.sectionsContainerFocusChanged.bind(this), false);
    this.sectionsContainer.addEventListener('focusout', this.sectionsContainerFocusChanged.bind(this), false);
    this.sectionByElement = new WeakMap();

    this.swatchPopoverHelperInternal = new InlineEditor.SwatchPopoverHelper.SwatchPopoverHelper();
    this.swatchPopoverHelperInternal.addEventListener(
        InlineEditor.SwatchPopoverHelper.Events.WillShowPopover, this.hideAllPopovers, this);
    this.linkifier = new Components.Linkifier.Linkifier(_maxLinkLength, /* useLinkDecorator */ true);
    this.decorator = new StylePropertyHighlighter(this);
    this.lastRevealedProperty = null;
    this.userOperation = false;
    this.isEditingStyle = false;
    this.filterRegexInternal = null;
    this.isActivePropertyHighlighted = false;
    this.initialUpdateCompleted = false;
    this.hasMatchedStyles = false;

    this.contentElement.classList.add('styles-pane');

    this.sectionBlocks = [];
    this.idleCallbackManager = null;
    this.needsForceUpdate = false;
    _stylesSidebarPaneInstance = this;
    UI.Context.Context.instance().addFlavorChangeListener(SDK.DOMModel.DOMNode, this.forceUpdate, this);
    this.contentElement.addEventListener('copy', this.clipboardCopy.bind(this));
    this.resizeThrottler = new Common.Throttler.Throttler(100);

    this.imagePreviewPopover = new ImagePreviewPopover(this.contentElement, event => {
      const link = event.composedPath()[0];
      if (link instanceof Element) {
        return link;
      }
      return null;
    }, () => this.node());

    this.activeCSSAngle = null;
  }

  swatchPopoverHelper(): InlineEditor.SwatchPopoverHelper.SwatchPopoverHelper {
    return this.swatchPopoverHelperInternal;
  }

  setUserOperation(userOperation: boolean): void {
    this.userOperation = userOperation;
  }

  static createExclamationMark(property: SDK.CSSProperty.CSSProperty, title: string|null): Element {
    const exclamationElement = (document.createElement('span', {is: 'dt-icon-label'}) as UI.UIUtils.DevToolsIconLabel);
    exclamationElement.className = 'exclamation-mark';
    if (!StylesSidebarPane.ignoreErrorsForProperty(property)) {
      exclamationElement.type = 'smallicon-warning';
    }
    let invalidMessage: string|Common.UIString.LocalizedString;
    if (title) {
      UI.Tooltip.Tooltip.install(exclamationElement, title);
      invalidMessage = title;
    } else {
      invalidMessage = SDK.CSSMetadata.cssMetadata().isCSSPropertyName(property.name) ?
          i18nString(UIStrings.invalidPropertyValue) :
          i18nString(UIStrings.unknownPropertyName);
      UI.Tooltip.Tooltip.install(exclamationElement, invalidMessage);
    }
    const invalidString =
        i18nString(UIStrings.invalidString, {PH1: invalidMessage, PH2: property.name, PH3: property.value});

    // Storing the invalidString for future screen reader support when editing the property
    property.setDisplayedStringForInvalidProperty(invalidString);

    return exclamationElement;
  }

  static ignoreErrorsForProperty(property: SDK.CSSProperty.CSSProperty): boolean {
    function hasUnknownVendorPrefix(string: string): boolean {
      return !string.startsWith('-webkit-') && /^[-_][\w\d]+-\w/.test(string);
    }

    const name = property.name.toLowerCase();

    // IE hack.
    if (name.charAt(0) === '_') {
      return true;
    }

    // IE has a different format for this.
    if (name === 'filter') {
      return true;
    }

    // Common IE-specific property prefix.
    if (name.startsWith('scrollbar-')) {
      return true;
    }
    if (hasUnknownVendorPrefix(name)) {
      return true;
    }

    const value = property.value.toLowerCase();

    // IE hack.
    if (value.endsWith('\\9')) {
      return true;
    }
    if (hasUnknownVendorPrefix(value)) {
      return true;
    }

    return false;
  }

  static createPropertyFilterElement(
      placeholder: string, container: Element, filterCallback: (arg0: RegExp|null) => void): Element {
    const input = document.createElement('input');
    input.type = 'search';
    input.classList.add('custom-search-input');
    input.placeholder = placeholder;

    function searchHandler(): void {
      const regex = input.value ? new RegExp(Platform.StringUtilities.escapeForRegExp(input.value), 'i') : null;
      filterCallback(regex);
    }
    input.addEventListener('input', searchHandler, false);

    function keydownHandler(event: Event): void {
      const keyboardEvent = (event as KeyboardEvent);
      if (keyboardEvent.key !== Platform.KeyboardUtilities.ESCAPE_KEY || !input.value) {
        return;
      }
      keyboardEvent.consume(true);
      input.value = '';
      searchHandler();
    }
    input.addEventListener('keydown', keydownHandler, false);
    return input;
  }

  static formatLeadingProperties(section: StylePropertiesSection): {
    allDeclarationText: string,
    ruleText: string,
  } {
    const selectorText = section.headerText();
    const indent = Common.Settings.Settings.instance().moduleSetting('textEditorIndent').get();

    const style = section.style();
    const lines: string[] = [];

    // Invalid property should also be copied.
    // For example: *display: inline.
    for (const property of style.leadingProperties()) {
      if (property.disabled) {
        lines.push(`${indent}/* ${property.name}: ${property.value}; */`);
      } else {
        lines.push(`${indent}${property.name}: ${property.value};`);
      }
    }

    const allDeclarationText: string = lines.join('\n');
    const ruleText: string = `${selectorText} {\n${allDeclarationText}\n}`;

    return {
      allDeclarationText,
      ruleText,
    };
  }

  revealProperty(cssProperty: SDK.CSSProperty.CSSProperty): void {
    this.decorator.highlightProperty(cssProperty);
    this.lastRevealedProperty = cssProperty;
    this.update();
  }

  jumpToProperty(propertyName: string): void {
    this.decorator.findAndHighlightPropertyName(propertyName);
  }

  forceUpdate(): void {
    this.needsForceUpdate = true;
    this.swatchPopoverHelperInternal.hide();
    this.resetCache();
    this.update();
  }

  private sectionsContainerKeyDown(event: Event): void {
    const activeElement = this.sectionsContainer.ownerDocument.deepActiveElement();
    if (!activeElement) {
      return;
    }
    const section = this.sectionByElement.get(activeElement);
    if (!section) {
      return;
    }
    let sectionToFocus: (StylePropertiesSection|null)|null = null;
    let willIterateForward = false;
    switch (/** @type {!KeyboardEvent} */ (event as KeyboardEvent).key) {
      case 'ArrowUp':
      case 'ArrowLeft': {
        sectionToFocus = section.previousSibling() || section.lastSibling();
        willIterateForward = false;
        break;
      }
      case 'ArrowDown':
      case 'ArrowRight': {
        sectionToFocus = section.nextSibling() || section.firstSibling();
        willIterateForward = true;
        break;
      }
      case 'Home': {
        sectionToFocus = section.firstSibling();
        willIterateForward = true;
        break;
      }
      case 'End': {
        sectionToFocus = section.lastSibling();
        willIterateForward = false;
        break;
      }
    }

    if (sectionToFocus && this.filterRegexInternal) {
      sectionToFocus = sectionToFocus.findCurrentOrNextVisible(/* willIterateForward= */ willIterateForward);
    }
    if (sectionToFocus) {
      sectionToFocus.element.focus();
      event.consume(true);
    }
  }

  private sectionsContainerFocusChanged(): void {
    this.resetFocus();
  }

  resetFocus(): void {
    // When a styles section is focused, shift+tab should leave the section.
    // Leaving tabIndex = 0 on the first element would cause it to be focused instead.
    if (!this.noMatchesElement.classList.contains('hidden')) {
      return;
    }
    if (this.sectionBlocks[0] && this.sectionBlocks[0].sections[0]) {
      const firstVisibleSection =
          this.sectionBlocks[0].sections[0].findCurrentOrNextVisible(/* willIterateForward= */ true);
      if (firstVisibleSection) {
        firstVisibleSection.element.tabIndex = this.sectionsContainer.hasFocus() ? -1 : 0;
      }
    }
  }

  onAddButtonLongClick(event: Event): void {
    const cssModel = this.cssModel();
    if (!cssModel) {
      return;
    }
    const headers = cssModel.styleSheetHeaders().filter(styleSheetResourceHeader);

    const contextMenuDescriptors: {
      text: string,
      handler: () => Promise<void>,
    }[] = [];
    for (let i = 0; i < headers.length; ++i) {
      const header = headers[i];
      const handler = this.createNewRuleInStyleSheet.bind(this, header);
      contextMenuDescriptors.push({text: Bindings.ResourceUtils.displayNameForURL(header.resourceURL()), handler});
    }

    contextMenuDescriptors.sort(compareDescriptors);

    const contextMenu = new UI.ContextMenu.ContextMenu(event);
    for (let i = 0; i < contextMenuDescriptors.length; ++i) {
      const descriptor = contextMenuDescriptors[i];
      contextMenu.defaultSection().appendItem(descriptor.text, descriptor.handler);
    }
    contextMenu.footerSection().appendItem(
        'inspector-stylesheet', this.createNewRuleInViaInspectorStyleSheet.bind(this));
    contextMenu.show();

    function compareDescriptors(
        descriptor1: {
          text: string,
          handler: () => Promise<void>,
        },
        descriptor2: {
          text: string,
          handler: () => Promise<void>,
        }): number {
      return Platform.StringUtilities.naturalOrderComparator(descriptor1.text, descriptor2.text);
    }

    function styleSheetResourceHeader(header: SDK.CSSStyleSheetHeader.CSSStyleSheetHeader): boolean {
      return !header.isViaInspector() && !header.isInline && Boolean(header.resourceURL());
    }
  }

  private onFilterChanged(regex: RegExp|null): void {
    this.filterRegexInternal = regex;
    this.updateFilter();
    this.resetFocus();
  }

  refreshUpdate(editedSection: StylePropertiesSection, editedTreeElement?: StylePropertyTreeElement): void {
    if (editedTreeElement) {
      for (const section of this.allSections()) {
        if (section instanceof BlankStylePropertiesSection && section.isBlank) {
          continue;
        }
        section.updateVarFunctions(editedTreeElement);
      }
    }

    if (this.isEditingStyle) {
      return;
    }
    const node = this.node();
    if (!node) {
      return;
    }

    for (const section of this.allSections()) {
      if (section instanceof BlankStylePropertiesSection && section.isBlank) {
        continue;
      }
      section.update(section === editedSection);
    }

    if (this.filterRegexInternal) {
      this.updateFilter();
    }
    this.swatchPopoverHelper().reposition();
    this.nodeStylesUpdatedForTest(node, false);
  }

  async doUpdate(): Promise<void> {
    if (!this.initialUpdateCompleted) {
      setTimeout(() => {
        if (!this.initialUpdateCompleted) {
          // the spinner will get automatically removed when innerRebuildUpdate is called
          this.sectionsContainer.createChild('span', 'spinner');
        }
      }, 200 /* only spin for loading time > 200ms to avoid unpleasant render flashes */);
    }

    const matchedStyles = await this.fetchMatchedCascade();
    await this.innerRebuildUpdate(matchedStyles);
    if (!this.initialUpdateCompleted) {
      this.initialUpdateCompleted = true;
      this.dispatchEventToListeners(Events.InitialUpdateCompleted);
    }

    this.dispatchEventToListeners(Events.StylesUpdateCompleted, {hasMatchedStyles: this.hasMatchedStyles});
  }

  onResize(): void {
    this.resizeThrottler.schedule(this.innerResize.bind(this));
  }

  private innerResize(): Promise<void> {
    const width = this.contentElement.getBoundingClientRect().width + 'px';
    this.allSections().forEach(section => {
      section.propertiesTreeOutline.element.style.width = width;
    });
    return Promise.resolve();
  }

  private resetCache(): void {
    const cssModel = this.cssModel();
    if (cssModel) {
      cssModel.discardCachedMatchedCascade();
    }
  }

  private fetchMatchedCascade(): Promise<SDK.CSSMatchedStyles.CSSMatchedStyles|null> {
    const node = this.node();
    if (!node || !this.cssModel()) {
      return Promise.resolve((null as SDK.CSSMatchedStyles.CSSMatchedStyles | null));
    }

    const cssModel = this.cssModel();
    if (!cssModel) {
      return Promise.resolve(null);
    }
    return cssModel.cachedMatchedCascadeForNode(node).then(validateStyles.bind(this));

    function validateStyles(this: StylesSidebarPane, matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles|null):
        SDK.CSSMatchedStyles.CSSMatchedStyles|null {
      return matchedStyles && matchedStyles.node() === this.node() ? matchedStyles : null;
    }
  }

  setEditingStyle(editing: boolean, _treeElement?: StylePropertyTreeElement): void {
    if (this.isEditingStyle === editing) {
      return;
    }
    this.contentElement.classList.toggle('is-editing-style', editing);
    this.isEditingStyle = editing;
    this.setActiveProperty(null);
  }

  setActiveProperty(treeElement: StylePropertyTreeElement|null): void {
    if (this.isActivePropertyHighlighted) {
      SDK.OverlayModel.OverlayModel.hideDOMNodeHighlight();
    }
    this.isActivePropertyHighlighted = false;

    if (!this.node()) {
      return;
    }

    if (!treeElement || treeElement.overloaded() || treeElement.inherited()) {
      return;
    }

    const rule = treeElement.property.ownerStyle.parentRule;
    const selectorList = (rule instanceof SDK.CSSRule.CSSStyleRule) ? rule.selectorText() : undefined;
    for (const {properties, mode} of HIGHLIGHTABLE_PROPERTIES) {
      if (!properties.includes(treeElement.name)) {
        continue;
      }
      const node = this.node();
      if (!node) {
        continue;
      }
      node.domModel().overlayModel().highlightInOverlay(
          {node: (this.node() as SDK.DOMModel.DOMNode), selectorList}, mode);
      this.isActivePropertyHighlighted = true;
      break;
    }
  }

  override onCSSModelChanged(event: Common.EventTarget.EventTargetEvent<ComputedStyleChangedEvent>): void {
    const edit = event?.data && 'edit' in event.data ? event.data.edit : null;
    if (edit) {
      for (const section of this.allSections()) {
        section.styleSheetEdited(edit);
      }
      return;
    }

    if (this.userOperation || this.isEditingStyle) {
      return;
    }

    this.resetCache();
    this.update();
  }

  focusedSectionIndex(): number {
    let index = 0;
    for (const block of this.sectionBlocks) {
      for (const section of block.sections) {
        if (section.element.hasFocus()) {
          return index;
        }
        index++;
      }
    }
    return -1;
  }

  continueEditingElement(sectionIndex: number, propertyIndex: number): void {
    const section = this.allSections()[sectionIndex];
    if (section) {
      const element = (section.closestPropertyForEditing(propertyIndex) as StylePropertyTreeElement | null);
      if (!element) {
        section.element.focus();
        return;
      }
      element.startEditing();
    }
  }

  private async innerRebuildUpdate(matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles|null): Promise<void> {
    // ElementsSidebarPane's throttler schedules this method. Usually,
    // rebuild is suppressed while editing (see onCSSModelChanged()), but we need a
    // 'force' flag since the currently running throttler process cannot be canceled.
    if (this.needsForceUpdate) {
      this.needsForceUpdate = false;
    } else if (this.isEditingStyle || this.userOperation) {
      return;
    }

    const focusedIndex = this.focusedSectionIndex();

    this.linkifier.reset();
    const prevSections = this.sectionBlocks.map(block => block.sections).flat();
    this.sectionBlocks = [];

    const node = this.node();
    this.hasMatchedStyles = matchedStyles !== null && node !== null;
    if (!this.hasMatchedStyles) {
      this.sectionsContainer.removeChildren();
      this.noMatchesElement.classList.remove('hidden');
      return;
    }

    this.sectionBlocks =
        await this.rebuildSectionsForMatchedStyleRules((matchedStyles as SDK.CSSMatchedStyles.CSSMatchedStyles));

    // Style sections maybe re-created when flexbox editor is activated.
    // With the following code we re-bind the flexbox editor to the new
    // section with the same index as the previous section had.
    const newSections = this.sectionBlocks.map(block => block.sections).flat();
    const styleEditorWidget = StyleEditorWidget.instance();
    const boundSection = styleEditorWidget.getSection();
    if (boundSection) {
      styleEditorWidget.unbindContext();
      for (const [index, prevSection] of prevSections.entries()) {
        if (boundSection === prevSection && index < newSections.length) {
          styleEditorWidget.bindContext(this, newSections[index]);
        }
      }
    }

    this.sectionsContainer.removeChildren();
    const fragment = document.createDocumentFragment();

    let index = 0;
    let elementToFocus: HTMLDivElement|null = null;
    for (const block of this.sectionBlocks) {
      const titleElement = block.titleElement();
      if (titleElement) {
        fragment.appendChild(titleElement);
      }
      for (const section of block.sections) {
        fragment.appendChild(section.element);
        if (index === focusedIndex) {
          elementToFocus = section.element;
        }
        index++;
      }
    }

    this.sectionsContainer.appendChild(fragment);

    if (elementToFocus) {
      elementToFocus.focus();
    }

    if (focusedIndex >= index) {
      this.sectionBlocks[0].sections[0].element.focus();
    }

    this.sectionsContainerFocusChanged();

    if (this.filterRegexInternal) {
      this.updateFilter();
    } else {
      this.noMatchesElement.classList.toggle('hidden', this.sectionBlocks.length > 0);
    }
    this.nodeStylesUpdatedForTest((node as SDK.DOMModel.DOMNode), true);
    if (this.lastRevealedProperty) {
      this.decorator.highlightProperty(this.lastRevealedProperty);
      this.lastRevealedProperty = null;
    }

    this.swatchPopoverHelper().reposition();

    // Record the elements tool load time after the sidepane has loaded.
    Host.userMetrics.panelLoaded('elements', 'DevTools.Launch.Elements');

    this.dispatchEventToListeners(Events.StylesUpdateCompleted, {hasMatchedStyles: false});
  }

  private nodeStylesUpdatedForTest(_node: SDK.DOMModel.DOMNode, _rebuild: boolean): void {
    // For sniffing in tests.
  }

  private async rebuildSectionsForMatchedStyleRules(matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles):
      Promise<SectionBlock[]> {
    if (this.idleCallbackManager) {
      this.idleCallbackManager.discard();
    }

    this.idleCallbackManager = new IdleCallbackManager();

    const blocks = [new SectionBlock(null)];
    let sectionIdx = 0;
    let lastParentNode: SDK.DOMModel.DOMNode|null = null;
    for (const style of matchedStyles.nodeStyles()) {
      const parentNode = matchedStyles.isInherited(style) ? matchedStyles.nodeForStyle(style) : null;
      if (parentNode && parentNode !== lastParentNode) {
        lastParentNode = parentNode;
        const block = await SectionBlock.createInheritedNodeBlock(lastParentNode);
        blocks.push(block);
      }

      const lastBlock = blocks[blocks.length - 1];
      if (lastBlock) {
        this.idleCallbackManager.schedule(() => {
          const section = new StylePropertiesSection(this, matchedStyles, style, sectionIdx);
          sectionIdx++;
          lastBlock.sections.push(section);
        });
      }
    }

    let pseudoTypes: Protocol.DOM.PseudoType[] = [];
    const keys = matchedStyles.pseudoTypes();
    if (keys.delete(Protocol.DOM.PseudoType.Before)) {
      pseudoTypes.push(Protocol.DOM.PseudoType.Before);
    }
    pseudoTypes = pseudoTypes.concat([...keys].sort());
    for (const pseudoType of pseudoTypes) {
      const block = SectionBlock.createPseudoTypeBlock(pseudoType);
      for (const style of matchedStyles.pseudoStyles(pseudoType)) {
        this.idleCallbackManager.schedule(() => {
          const section = new StylePropertiesSection(this, matchedStyles, style, sectionIdx);
          sectionIdx++;
          block.sections.push(section);
        });
      }
      blocks.push(block);
    }

    for (const keyframesRule of matchedStyles.keyframes()) {
      const block = SectionBlock.createKeyframesBlock(keyframesRule.name().text);
      for (const keyframe of keyframesRule.keyframes()) {
        this.idleCallbackManager.schedule(() => {
          block.sections.push(new KeyframePropertiesSection(this, matchedStyles, keyframe.style, sectionIdx));
          sectionIdx++;
        });
      }
      blocks.push(block);
    }

    await this.idleCallbackManager.awaitDone();

    return blocks;
  }

  async createNewRuleInViaInspectorStyleSheet(): Promise<void> {
    const cssModel = this.cssModel();
    const node = this.node();
    if (!cssModel || !node) {
      return;
    }
    this.setUserOperation(true);

    const styleSheetHeader = await cssModel.requestViaInspectorStylesheet((node as SDK.DOMModel.DOMNode));

    this.setUserOperation(false);
    await this.createNewRuleInStyleSheet(styleSheetHeader);
  }

  private async createNewRuleInStyleSheet(styleSheetHeader: SDK.CSSStyleSheetHeader.CSSStyleSheetHeader|
                                          null): Promise<void> {
    if (!styleSheetHeader) {
      return;
    }

    const text = (await styleSheetHeader.requestContent()).content || '';
    const lines = text.split('\n');
    const range = TextUtils.TextRange.TextRange.createFromLocation(lines.length - 1, lines[lines.length - 1].length);

    if (this.sectionBlocks && this.sectionBlocks.length > 0) {
      this.addBlankSection(this.sectionBlocks[0].sections[0], styleSheetHeader.id, range);
    }
  }

  addBlankSection(
      insertAfterSection: StylePropertiesSection, styleSheetId: Protocol.CSS.StyleSheetId,
      ruleLocation: TextUtils.TextRange.TextRange): void {
    const node = this.node();
    const blankSection = new BlankStylePropertiesSection(
        this, insertAfterSection.matchedStyles, node ? node.simpleSelector() : '', styleSheetId, ruleLocation,
        insertAfterSection.style(), 0);

    this.sectionsContainer.insertBefore(blankSection.element, insertAfterSection.element.nextSibling);

    for (const block of this.sectionBlocks) {
      const index = block.sections.indexOf(insertAfterSection);
      if (index === -1) {
        continue;
      }
      block.sections.splice(index + 1, 0, blankSection);
      blankSection.startEditingSelector();
    }
    let sectionIdx = 0;
    for (const block of this.sectionBlocks) {
      for (const section of block.sections) {
        section.setSectionIdx(sectionIdx);
        sectionIdx++;
      }
    }
  }

  removeSection(section: StylePropertiesSection): void {
    for (const block of this.sectionBlocks) {
      const index = block.sections.indexOf(section);
      if (index === -1) {
        continue;
      }
      block.sections.splice(index, 1);
      section.element.remove();
    }
  }

  filterRegex(): RegExp|null {
    return this.filterRegexInternal;
  }

  private updateFilter(): void {
    let hasAnyVisibleBlock = false;
    for (const block of this.sectionBlocks) {
      hasAnyVisibleBlock = block.updateFilter() || hasAnyVisibleBlock;
    }
    this.noMatchesElement.classList.toggle('hidden', Boolean(hasAnyVisibleBlock));
  }

  willHide(): void {
    this.hideAllPopovers();
    super.willHide();
  }

  hideAllPopovers(): void {
    this.swatchPopoverHelperInternal.hide();
    this.imagePreviewPopover.hide();
    if (this.activeCSSAngle) {
      this.activeCSSAngle.minify();
      this.activeCSSAngle = null;
    }
  }

  allSections(): StylePropertiesSection[] {
    let sections: StylePropertiesSection[] = [];
    for (const block of this.sectionBlocks) {
      sections = sections.concat(block.sections);
    }
    return sections;
  }

  private clipboardCopy(_event: Event): void {
    Host.userMetrics.actionTaken(Host.UserMetrics.Action.StyleRuleCopied);
  }

  private createStylesSidebarToolbar(): HTMLElement {
    const container = this.contentElement.createChild('div', 'styles-sidebar-pane-toolbar-container');
    const hbox = container.createChild('div', 'hbox styles-sidebar-pane-toolbar');
    const filterContainerElement = hbox.createChild('div', 'styles-sidebar-pane-filter-box');
    const filterInput = StylesSidebarPane.createPropertyFilterElement(
        i18nString(UIStrings.filter), hbox, this.onFilterChanged.bind(this));
    UI.ARIAUtils.setAccessibleName(filterInput, i18nString(UIStrings.filterStyles));
    filterContainerElement.appendChild(filterInput);
    const toolbar = new UI.Toolbar.Toolbar('styles-pane-toolbar', hbox);
    toolbar.makeToggledGray();
    toolbar.appendItemsAtLocation('styles-sidebarpane-toolbar');
    this.toolbar = toolbar;
    const toolbarPaneContainer = container.createChild('div', 'styles-sidebar-toolbar-pane-container');
    const toolbarPaneContent = (toolbarPaneContainer.createChild('div', 'styles-sidebar-toolbar-pane') as HTMLElement);

    return toolbarPaneContent;
  }

  showToolbarPane(widget: UI.Widget.Widget|null, toggle: UI.Toolbar.ToolbarToggle|null): void {
    if (this.pendingWidgetToggle) {
      this.pendingWidgetToggle.setToggled(false);
    }
    this.pendingWidgetToggle = toggle;

    if (this.animatedToolbarPane) {
      this.pendingWidget = widget;
    } else {
      this.startToolbarPaneAnimation(widget);
    }

    if (widget && toggle) {
      toggle.setToggled(true);
    }
  }

  appendToolbarItem(item: UI.Toolbar.ToolbarItem): void {
    if (this.toolbar) {
      this.toolbar.appendToolbarItem(item);
    }
  }

  private startToolbarPaneAnimation(widget: UI.Widget.Widget|null): void {
    if (widget === this.currentToolbarPane) {
      return;
    }

    if (widget && this.currentToolbarPane) {
      this.currentToolbarPane.detach();
      widget.show(this.toolbarPaneElement);
      this.currentToolbarPane = widget;
      this.currentToolbarPane.focus();
      return;
    }

    this.animatedToolbarPane = widget;

    if (this.currentToolbarPane) {
      this.toolbarPaneElement.style.animationName = 'styles-element-state-pane-slideout';
    } else if (widget) {
      this.toolbarPaneElement.style.animationName = 'styles-element-state-pane-slidein';
    }

    if (widget) {
      widget.show(this.toolbarPaneElement);
    }

    const listener = onAnimationEnd.bind(this);
    this.toolbarPaneElement.addEventListener('animationend', listener, false);

    function onAnimationEnd(this: StylesSidebarPane): void {
      this.toolbarPaneElement.style.removeProperty('animation-name');
      this.toolbarPaneElement.removeEventListener('animationend', listener, false);

      if (this.currentToolbarPane) {
        this.currentToolbarPane.detach();
      }

      this.currentToolbarPane = this.animatedToolbarPane;
      if (this.currentToolbarPane) {
        this.currentToolbarPane.focus();
      }
      this.animatedToolbarPane = null;

      if (this.pendingWidget) {
        this.startToolbarPaneAnimation(this.pendingWidget);
        this.pendingWidget = null;
      }
    }
  }
}

export const enum Events {
  InitialUpdateCompleted = 'InitialUpdateCompleted',
  StylesUpdateCompleted = 'StylesUpdateCompleted',
}

export interface StylesUpdateCompletedEvent {
  hasMatchedStyles: boolean;
}

export type EventTypes = {
  [Events.InitialUpdateCompleted]: void,
  [Events.StylesUpdateCompleted]: StylesUpdateCompletedEvent,
};

// TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
// eslint-disable-next-line @typescript-eslint/naming-convention
export const _maxLinkLength = 23;

export class SectionBlock {
  private readonly titleElementInternal: Element|null;
  sections: StylePropertiesSection[];
  constructor(titleElement: Element|null) {
    this.titleElementInternal = titleElement;
    this.sections = [];
  }

  static createPseudoTypeBlock(pseudoType: Protocol.DOM.PseudoType): SectionBlock {
    const separatorElement = document.createElement('div');
    separatorElement.className = 'sidebar-separator';
    separatorElement.textContent = i18nString(UIStrings.pseudoSElement, {PH1: pseudoType});
    return new SectionBlock(separatorElement);
  }

  static createKeyframesBlock(keyframesName: string): SectionBlock {
    const separatorElement = document.createElement('div');
    separatorElement.className = 'sidebar-separator';
    separatorElement.textContent = `@keyframes ${keyframesName}`;
    return new SectionBlock(separatorElement);
  }

  static async createInheritedNodeBlock(node: SDK.DOMModel.DOMNode): Promise<SectionBlock> {
    const separatorElement = document.createElement('div');
    separatorElement.className = 'sidebar-separator';
    UI.UIUtils.createTextChild(separatorElement, i18nString(UIStrings.inheritedFroms));
    const link = await Common.Linkifier.Linkifier.linkify(node, {
      preventKeyboardFocus: true,
      tooltip: undefined,
    });
    separatorElement.appendChild(link);
    return new SectionBlock(separatorElement);
  }

  updateFilter(): boolean {
    let hasAnyVisibleSection = false;
    for (const section of this.sections) {
      hasAnyVisibleSection = section.updateFilter() || hasAnyVisibleSection;
    }
    if (this.titleElementInternal) {
      this.titleElementInternal.classList.toggle('hidden', !hasAnyVisibleSection);
    }
    return Boolean(hasAnyVisibleSection);
  }

  titleElement(): Element|null {
    return this.titleElementInternal;
  }
}

export class IdleCallbackManager {
  private discarded: boolean;
  private readonly promises: Promise<void>[];
  constructor() {
    this.discarded = false;
    this.promises = [];
  }

  discard(): void {
    this.discarded = true;
  }

  schedule(fn: () => void, timeout: number = 100): void {
    if (this.discarded) {
      return;
    }
    this.promises.push(new Promise((resolve, reject) => {
      const run = (): void => {
        try {
          fn();
          resolve();
        } catch (err) {
          reject(err);
        }
      };
      window.requestIdleCallback(() => {
        if (this.discarded) {
          return resolve();
        }
        run();
      }, {timeout});
    }));
  }

  awaitDone(): Promise<void[]> {
    return Promise.all(this.promises);
  }
}

export class StylePropertiesSection {
  protected parentPane: StylesSidebarPane;
  styleInternal: SDK.CSSStyleDeclaration.CSSStyleDeclaration;
  readonly matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles;
  editable: boolean;
  private hoverTimer: number|null;
  private willCauseCancelEditing: boolean;
  private forceShowAll: boolean;
  private readonly originalPropertiesCount: number;
  element: HTMLDivElement;
  private readonly innerElement: HTMLElement;
  private readonly titleElement: HTMLElement;
  propertiesTreeOutline: UI.TreeOutline.TreeOutlineInShadow;
  private showAllButton: HTMLButtonElement;
  protected selectorElement: HTMLSpanElement;
  private readonly newStyleRuleToolbar: UI.Toolbar.Toolbar|undefined;
  private readonly fontEditorToolbar: UI.Toolbar.Toolbar|undefined;
  private readonly fontEditorSectionManager: FontEditorSectionManager|undefined;
  private readonly fontEditorButton: UI.Toolbar.ToolbarButton|undefined;
  private selectedSinceMouseDown: boolean;
  private readonly elementToSelectorIndex: WeakMap<Element, number>;
  navigable: boolean|null|undefined;
  protected readonly selectorRefElement: HTMLElement;
  private readonly selectorContainer: HTMLDivElement;
  private readonly fontPopoverIcon: FontEditorSectionManager|null;
  private hoverableSelectorsMode: boolean;
  private isHiddenInternal: boolean;

  private queryListElement: HTMLElement;

  // Used to identify buttons that trigger a flexbox or grid editor.
  nextEditorTriggerButtonIdx = 1;
  private sectionIdx = 0;

  constructor(
      parentPane: StylesSidebarPane, matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles,
      style: SDK.CSSStyleDeclaration.CSSStyleDeclaration, sectionIdx: number) {
    this.parentPane = parentPane;
    this.sectionIdx = sectionIdx;
    this.styleInternal = style;
    this.matchedStyles = matchedStyles;
    this.editable = Boolean(style.styleSheetId && style.range);
    this.hoverTimer = null;
    this.willCauseCancelEditing = false;
    this.forceShowAll = false;
    this.originalPropertiesCount = style.leadingProperties().length;

    const rule = style.parentRule;
    this.element = document.createElement('div');
    this.element.classList.add('styles-section');
    this.element.classList.add('matched-styles');
    this.element.classList.add('monospace');
    UI.ARIAUtils.setAccessibleName(this.element, `${this.headerText()}, css selector`);
    this.element.tabIndex = -1;
    UI.ARIAUtils.markAsListitem(this.element);
    this.element.addEventListener('keydown', this.onKeyDown.bind(this), false);
    parentPane.sectionByElement.set(this.element, this);
    this.innerElement = this.element.createChild('div');

    this.titleElement = this.innerElement.createChild('div', 'styles-section-title ' + (rule ? 'styles-selector' : ''));

    this.propertiesTreeOutline = new UI.TreeOutline.TreeOutlineInShadow();
    this.propertiesTreeOutline.setFocusable(false);
    this.propertiesTreeOutline.registerCSSFiles([stylesSectionTreeStyles]);
    this.propertiesTreeOutline.element.classList.add('style-properties', 'matched-styles', 'monospace');
    // @ts-ignore TODO: fix ad hoc section property in a separate CL to be safe
    this.propertiesTreeOutline.section = this;
    this.innerElement.appendChild(this.propertiesTreeOutline.element);

    this.showAllButton = UI.UIUtils.createTextButton('', this.showAllItems.bind(this), 'styles-show-all');
    this.innerElement.appendChild(this.showAllButton);

    const selectorContainer = document.createElement('div');
    this.selectorElement = document.createElement('span');
    UI.ARIAUtils.setAccessibleName(this.selectorElement, i18nString(UIStrings.cssSelector));
    this.selectorElement.classList.add('selector');
    this.selectorElement.textContent = this.headerText();
    selectorContainer.appendChild(this.selectorElement);
    this.selectorElement.addEventListener('mouseenter', this.onMouseEnterSelector.bind(this), false);
    this.selectorElement.addEventListener('mousemove', event => event.consume(), false);
    this.selectorElement.addEventListener('mouseleave', this.onMouseOutSelector.bind(this), false);

    const openBrace = selectorContainer.createChild('span', 'sidebar-pane-open-brace');
    openBrace.textContent = ' {';
    selectorContainer.addEventListener('mousedown', this.handleEmptySpaceMouseDown.bind(this), false);
    selectorContainer.addEventListener('click', this.handleSelectorContainerClick.bind(this), false);

    const closeBrace = this.innerElement.createChild('div', 'sidebar-pane-closing-brace');
    closeBrace.textContent = '}';

    if (this.styleInternal.parentRule) {
      const newRuleButton = new UI.Toolbar.ToolbarButton(i18nString(UIStrings.insertStyleRuleBelow), 'largeicon-add');
      newRuleButton.addEventListener(UI.Toolbar.ToolbarButton.Events.Click, this.onNewRuleClick, this);
      newRuleButton.element.tabIndex = -1;
      if (!this.newStyleRuleToolbar) {
        this.newStyleRuleToolbar =
            new UI.Toolbar.Toolbar('sidebar-pane-section-toolbar new-rule-toolbar', this.innerElement);
      }
      this.newStyleRuleToolbar.appendToolbarItem(newRuleButton);
      UI.ARIAUtils.markAsHidden(this.newStyleRuleToolbar.element);
    }

    if (Root.Runtime.experiments.isEnabled('fontEditor') && this.editable) {
      this.fontEditorToolbar = new UI.Toolbar.Toolbar('sidebar-pane-section-toolbar', this.innerElement);
      this.fontEditorSectionManager = new FontEditorSectionManager(this.parentPane.swatchPopoverHelper(), this);
      this.fontEditorButton = new UI.Toolbar.ToolbarButton('Font Editor', 'largeicon-font-editor');
      this.fontEditorButton.addEventListener(UI.Toolbar.ToolbarButton.Events.Click, () => {
        this.onFontEditorButtonClicked();
      }, this);
      this.fontEditorButton.element.addEventListener('keydown', event => {
        if (isEnterOrSpaceKey(event)) {
          event.consume(true);
          this.onFontEditorButtonClicked();
        }
      }, false);
      this.fontEditorToolbar.appendToolbarItem(this.fontEditorButton);

      if (this.styleInternal.type === SDK.CSSStyleDeclaration.Type.Inline) {
        if (this.newStyleRuleToolbar) {
          this.newStyleRuleToolbar.element.classList.add('shifted-toolbar');
        }
      } else {
        this.fontEditorToolbar.element.classList.add('font-toolbar-hidden');
      }
    }

    this.selectorElement.addEventListener('click', this.handleSelectorClick.bind(this), false);
    this.element.addEventListener('contextmenu', this.handleContextMenuEvent.bind(this), false);
    this.element.addEventListener('mousedown', this.handleEmptySpaceMouseDown.bind(this), false);
    this.element.addEventListener('click', this.handleEmptySpaceClick.bind(this), false);
    this.element.addEventListener('mousemove', this.onMouseMove.bind(this), false);
    this.element.addEventListener('mouseleave', this.onMouseLeave.bind(this), false);
    this.selectedSinceMouseDown = false;

    this.elementToSelectorIndex = new WeakMap();

    if (rule) {
      // Prevent editing the user agent and user rules.
      if (rule.isUserAgent() || rule.isInjected()) {
        this.editable = false;
      } else {
        // Check this is a real CSSRule, not a bogus object coming from BlankStylePropertiesSection.
        if (rule.styleSheetId) {
          const header = rule.cssModel().styleSheetHeaderForId(rule.styleSheetId);
          this.navigable = header && !header.isAnonymousInlineStyleSheet();
        }
      }
    }

    this.queryListElement = this.titleElement.createChild('div', 'query-list query-matches');
    this.selectorRefElement = this.titleElement.createChild('div', 'styles-section-subtitle');
    this.updateQueryList();
    this.updateRuleOrigin();
    this.titleE