Bug 1801193 - Focus panel buttons when screenshots UI is opened. r=sfoster,cmkm

Differential Revision: https://phabricator.services.mozilla.com/D162333

browser/base/content/main-popupset.inc.xhtml

@@ -162,7 +162,6 @@
     <panel id="screenshotsPagePanel"
            type="arrow"
            orient="vertical"
-           noautofocus="true"
            norolluponanchor="true"
            consumeoutsideclicks="never"
            level="parent"

browser/components/screenshots/tests/browser/browser.ini

@@ -10,6 +10,7 @@ prefs =
 
 [browser_screenshots_drag_scroll_test.js]
 [browser_screenshots_drag_test.js]
+[browser_screenshots_focus_test.js]
 [browser_screenshots_overlay_panel_sync.js]
 [browser_screenshots_page_unload.js]
 [browser_screenshots_short_page_test.js]

browser/components/screenshots/tests/browser/browser_screenshots_focus_test.js

@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function testPanelFocused() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      let helper = new ScreenshotsHelper(browser);
+
+      helper.triggerUIFromToolbar();
+
+      await helper.waitForOverlay();
+
+      EventUtils.synthesizeKey("KEY_Tab");
+
+      let screenshotsButtons = gBrowser.selectedBrowser.ownerDocument
+        .querySelector("#screenshotsPagePanel")
+        .querySelector("screenshots-buttons").shadowRoot;
+
+      let focusedElement = screenshotsButtons.querySelector(".visible-page");
+
+      is(
+        focusedElement,
+        screenshotsButtons.activeElement,
+        "Visible button is focused"
+      );
+    }
+  );
+});