forked from mirrors/gecko-dev
496eb6907f
Since the keyboar navigation is handled in a custom way on toolbars, it is automatically includes any element with `role="button"` in the custom focus order, overwriting the default behavior. But since we have a limited number of controls that function as a submit buttons for the URL and Search bars and this functionality is redundant for keyboard users (who could press `Enter` instead of navigating to this control and pressing an `Enter`), we want to reduce the strain of navigation and exclude those elements from the focus order - even from the custom focus handling. At the same time, we want to keep the interactive role to allow assistive technology to interact with these element, should their users choose to do so. In this patch, we are adding new `keyNav` attribute to a programmatic button and ensuring the `browser_toolbarKeyNav.js` handler does not include this element in the custom focus order. This would remove a keyboard trap created by the regressor bug 1871596 and would allow for better handling of these exceptions in the future. Differential Revision: https://phabricator.services.mozilla.com/D199309
435 lines
14 KiB
JavaScript
435 lines
14 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// This file is loaded into the browser window scope.
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/* eslint-env mozilla/browser-window */
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/**
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* Handle keyboard navigation for toolbars.
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* Having separate tab stops for every toolbar control results in an
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* unmanageable number of tab stops. Therefore, we group buttons under a single
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* tab stop and allow movement between them using left/right arrows.
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* However, text inputs use the arrow keys for their own purposes, so they need
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* their own tab stop. There are also groups of buttons before and after the
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* URL bar input which should get their own tab stop. The subsequent buttons on
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* the toolbar are then another tab stop after that.
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* Tab stops for groups of buttons are set using the <toolbartabstop/> element.
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* This element is invisible, but gets included in the tab order. When one of
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* these gets focus, it redirects focus to the appropriate button. This avoids
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* the need to continually manage the tabindex of toolbar buttons in response to
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* toolbarchanges.
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* In addition to linear navigation with tab and arrows, users can also type
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* the first (or first few) characters of a button's name to jump directly to
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* that button.
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*/
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ToolbarKeyboardNavigator = {
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// Toolbars we want to be keyboard navigable.
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kToolbars: [
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CustomizableUI.AREA_TABSTRIP,
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CustomizableUI.AREA_NAVBAR,
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CustomizableUI.AREA_BOOKMARKS,
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],
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// Delay (in ms) after which to clear any search text typed by the user if
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// the user hasn't typed anything further.
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kSearchClearTimeout: 1000,
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_isButton(aElem) {
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if (aElem.getAttribute("keyNav") === "false") {
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return false;
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}
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return (
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aElem.tagName == "toolbarbutton" || aElem.getAttribute("role") == "button"
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);
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},
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// Get a TreeWalker which includes only controls which should be keyboard
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// navigable.
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_getWalker(aRoot) {
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if (aRoot._toolbarKeyNavWalker) {
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return aRoot._toolbarKeyNavWalker;
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}
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let filter = aNode => {
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if (aNode.tagName == "toolbartabstop") {
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return NodeFilter.FILTER_ACCEPT;
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}
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// Special case for the "View site information" button, which isn't
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// actionable in some cases but is still visible.
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if (
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aNode.id == "identity-box" &&
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document.getElementById("urlbar").getAttribute("pageproxystate") ==
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"invalid"
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) {
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return NodeFilter.FILTER_REJECT;
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}
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// Skip disabled elements.
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if (aNode.disabled) {
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return NodeFilter.FILTER_REJECT;
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}
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// Skip invisible elements.
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const visible = aNode.checkVisibility({
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checkVisibilityCSS: true,
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flush: false,
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});
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if (!visible) {
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return NodeFilter.FILTER_REJECT;
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}
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// This width check excludes the overflow button when there's no overflow.
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const bounds = window.windowUtils.getBoundsWithoutFlushing(aNode);
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if (bounds.width == 0) {
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return NodeFilter.FILTER_SKIP;
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}
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if (this._isButton(aNode)) {
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return NodeFilter.FILTER_ACCEPT;
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}
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return NodeFilter.FILTER_SKIP;
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};
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aRoot._toolbarKeyNavWalker = document.createTreeWalker(
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aRoot,
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NodeFilter.SHOW_ELEMENT,
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filter
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);
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return aRoot._toolbarKeyNavWalker;
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},
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_initTabStops(aRoot) {
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for (let stop of aRoot.getElementsByTagName("toolbartabstop")) {
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// These are invisible, but because they need to be in the tab order,
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// they can't get display: none or similar. They must therefore be
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// explicitly hidden for accessibility.
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stop.setAttribute("aria-hidden", "true");
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stop.addEventListener("focus", this);
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}
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},
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init() {
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for (let id of this.kToolbars) {
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let toolbar = document.getElementById(id);
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// When enabled, no toolbar buttons should themselves be tabbable.
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// We manage toolbar focus completely. This attribute ensures that CSS
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// doesn't set -moz-user-focus: normal.
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toolbar.setAttribute("keyNav", "true");
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this._initTabStops(toolbar);
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toolbar.addEventListener("keydown", this);
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toolbar.addEventListener("keypress", this);
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}
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CustomizableUI.addListener(this);
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},
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uninit() {
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for (let id of this.kToolbars) {
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let toolbar = document.getElementById(id);
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for (let stop of toolbar.getElementsByTagName("toolbartabstop")) {
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stop.removeEventListener("focus", this);
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}
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toolbar.removeEventListener("keydown", this);
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toolbar.removeEventListener("keypress", this);
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toolbar.removeAttribute("keyNav");
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}
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CustomizableUI.removeListener(this);
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},
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// CustomizableUI event handler
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onWidgetAdded(aWidgetId, aArea, aPosition) {
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if (!this.kToolbars.includes(aArea)) {
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return;
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}
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let widget = document.getElementById(aWidgetId);
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if (!widget) {
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return;
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}
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this._initTabStops(widget);
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},
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_focusButton(aButton) {
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// Toolbar buttons aren't focusable because if they were, clicking them
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// would focus them, which is undesirable. Therefore, we must make a
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// button focusable only when we want to focus it.
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aButton.setAttribute("tabindex", "-1");
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aButton.focus();
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// We could remove tabindex now, but even though the button keeps DOM
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// focus, a11y gets confused because the button reports as not being
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// focusable. This results in weirdness if the user switches windows and
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// then switches back. It also means that focus can't be restored to the
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// button when a panel is closed. Instead, remove tabindex when the button
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// loses focus.
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aButton.addEventListener("blur", this);
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},
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_onButtonBlur(aEvent) {
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if (document.activeElement == aEvent.target) {
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// This event was fired because the user switched windows. This button
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// will get focus again when the user returns.
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return;
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}
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if (aEvent.target.getAttribute("open") == "true") {
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// The button activated a panel. The button should remain
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// focusable so that focus can be restored when the panel closes.
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return;
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}
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aEvent.target.removeEventListener("blur", this);
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aEvent.target.removeAttribute("tabindex");
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},
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_onTabStopFocus(aEvent) {
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let toolbar = aEvent.target.closest("toolbar");
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let walker = this._getWalker(toolbar);
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let oldFocus = aEvent.relatedTarget;
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if (oldFocus) {
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// Save this because we might rewind focus and the subsequent focus event
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// won't get a relatedTarget.
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this._isFocusMovingBackward =
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oldFocus.compareDocumentPosition(aEvent.target) &
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Node.DOCUMENT_POSITION_PRECEDING;
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if (this._isFocusMovingBackward && oldFocus && this._isButton(oldFocus)) {
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// Shift+tabbing from a button will land on its toolbartabstop. Skip it.
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document.commandDispatcher.rewindFocus();
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return;
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}
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}
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walker.currentNode = aEvent.target;
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let button = walker.nextNode();
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if (!button || !this._isButton(button)) {
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// If we think we're moving backward, and focus came from outside the
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// toolbox, we might actually have wrapped around. In this case, the
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// event target was the first tabstop. If we can't find a button, e.g.
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// because we're in a popup where most buttons are hidden, we
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// should ensure focus keeps moving forward:
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if (
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this._isFocusMovingBackward &&
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(!oldFocus || !gNavToolbox.contains(oldFocus))
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) {
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let allStops = Array.from(
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gNavToolbox.querySelectorAll("toolbartabstop")
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);
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// Find the previous toolbartabstop:
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let earlierVisibleStopIndex = allStops.indexOf(aEvent.target) - 1;
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// Then work out if any of the earlier ones are in a visible
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// toolbar:
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while (earlierVisibleStopIndex >= 0) {
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let stopToolbar =
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allStops[earlierVisibleStopIndex].closest("toolbar");
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if (!stopToolbar.collapsed) {
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break;
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}
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earlierVisibleStopIndex--;
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}
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// If we couldn't find any earlier visible stops, we're not moving
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// backwards, we're moving forwards and wrapped around:
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if (earlierVisibleStopIndex == -1) {
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this._isFocusMovingBackward = false;
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}
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}
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// No navigable buttons for this tab stop. Skip it.
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if (this._isFocusMovingBackward) {
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document.commandDispatcher.rewindFocus();
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} else {
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document.commandDispatcher.advanceFocus();
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}
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return;
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}
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this._focusButton(button);
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},
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navigateButtons(aToolbar, aPrevious) {
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let oldFocus = document.activeElement;
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let walker = this._getWalker(aToolbar);
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// Start from the current control and walk to the next/previous control.
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walker.currentNode = oldFocus;
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let newFocus;
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if (aPrevious) {
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newFocus = walker.previousNode();
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} else {
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newFocus = walker.nextNode();
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}
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if (!newFocus || newFocus.tagName == "toolbartabstop") {
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// There are no more controls or we hit a tab stop placeholder.
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return;
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}
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this._focusButton(newFocus);
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},
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_onKeyDown(aEvent) {
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let focus = document.activeElement;
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if (
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aEvent.key != " " &&
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aEvent.key.length == 1 &&
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this._isButton(focus) &&
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// Don't handle characters if the user is focused in a panel anchored
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// to the toolbar.
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!focus.closest("panel")
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) {
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this._onSearchChar(aEvent.currentTarget, aEvent.key);
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return;
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}
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// Anything that doesn't trigger search should clear the search.
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this._clearSearch();
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if (
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aEvent.altKey ||
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aEvent.controlKey ||
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aEvent.metaKey ||
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aEvent.shiftKey ||
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!this._isButton(focus)
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) {
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return;
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}
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switch (aEvent.key) {
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case "ArrowLeft":
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// Previous if UI is LTR, next if UI is RTL.
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this.navigateButtons(aEvent.currentTarget, !window.RTL_UI);
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break;
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case "ArrowRight":
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// Previous if UI is RTL, next if UI is LTR.
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this.navigateButtons(aEvent.currentTarget, window.RTL_UI);
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break;
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default:
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return;
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}
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aEvent.preventDefault();
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},
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_clearSearch() {
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this._searchText = "";
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if (this._clearSearchTimeout) {
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clearTimeout(this._clearSearchTimeout);
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this._clearSearchTimeout = null;
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}
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},
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_onSearchChar(aToolbar, aChar) {
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if (this._clearSearchTimeout) {
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// The user just typed a character, so reset the timer.
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clearTimeout(this._clearSearchTimeout);
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}
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// Convert to lower case so we can do case insensitive searches.
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let char = aChar.toLowerCase();
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// If the user has only typed a single character and they type the same
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// character again, they want to move to the next item starting with that
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// same character. Effectively, it's as if there was no existing search.
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// In that case, we just leave this._searchText alone.
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if (!this._searchText) {
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this._searchText = char;
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} else if (this._searchText != char) {
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this._searchText += char;
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}
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// Clear the search if the user doesn't type anything more within the timeout.
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this._clearSearchTimeout = setTimeout(
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this._clearSearch.bind(this),
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this.kSearchClearTimeout
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);
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let oldFocus = document.activeElement;
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let walker = this._getWalker(aToolbar);
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// Search forward after the current control.
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walker.currentNode = oldFocus;
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for (
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let newFocus = walker.nextNode();
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newFocus;
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newFocus = walker.nextNode()
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) {
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if (this._doesSearchMatch(newFocus)) {
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this._focusButton(newFocus);
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return;
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}
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}
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// No match, so search from the start until the current control.
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walker.currentNode = walker.root;
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for (
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let newFocus = walker.firstChild();
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newFocus && newFocus != oldFocus;
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newFocus = walker.nextNode()
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) {
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if (this._doesSearchMatch(newFocus)) {
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this._focusButton(newFocus);
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return;
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}
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}
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},
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_doesSearchMatch(aElem) {
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if (!this._isButton(aElem)) {
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return false;
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}
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for (let attrib of ["aria-label", "label", "tooltiptext"]) {
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let label = aElem.getAttribute(attrib);
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if (!label) {
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continue;
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}
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// Convert to lower case so we do a case insensitive comparison.
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// (this._searchText is already lower case.)
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label = label.toLowerCase();
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if (label.startsWith(this._searchText)) {
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return true;
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}
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}
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return false;
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},
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_onKeyPress(aEvent) {
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let focus = document.activeElement;
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if (
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(aEvent.key != "Enter" && aEvent.key != " ") ||
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!this._isButton(focus)
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) {
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return;
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}
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if (focus.getAttribute("type") == "menu") {
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focus.open = true;
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return;
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}
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// Several buttons specifically don't use command events; e.g. because
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// they want to activate for middle click. Therefore, simulate a click
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// event if we know they handle click explicitly and don't handle
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// commands.
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const usesClickInsteadOfCommand = (() => {
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if (focus.tagName != "toolbarbutton") {
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return true;
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}
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return !focus.hasAttribute("oncommand") && focus.hasAttribute("onclick");
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})();
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if (!usesClickInsteadOfCommand) {
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return;
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}
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focus.dispatchEvent(
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new MouseEvent("click", {
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bubbles: true,
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ctrlKey: aEvent.ctrlKey,
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altKey: aEvent.altKey,
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shiftKey: aEvent.shiftKey,
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metaKey: aEvent.metaKey,
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})
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);
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},
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handleEvent(aEvent) {
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switch (aEvent.type) {
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case "focus":
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this._onTabStopFocus(aEvent);
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break;
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case "keydown":
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this._onKeyDown(aEvent);
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break;
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case "keypress":
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this._onKeyPress(aEvent);
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break;
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case "blur":
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this._onButtonBlur(aEvent);
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break;
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}
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},
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};
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