Backport PR #13103 on branch 3.4.x (Switch back to display to hide ta…

…bs) (#13123)

* Backport PR #13103: Switch back to `display` to hide tabs

* Fix cell content for CodeMirror 5

galata/test/jupyterlab/help.test.ts

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) Jupyter Development Team.
+ * Distributed under the terms of the Modified BSD License.
+ */
+
+import { expect, test } from '@jupyterlab/galata';
+
+test('Switch back and forth to reference page', async ({ page }) => {
+  // The goal is to test switching back and forth with a tab containing an iframe
+  const notebookFilename = 'test-switch-doc-notebook';
+  const cellContent = '# First cell';
+  await page.notebook.createNew(notebookFilename);
+
+  await page.notebook.setCell(0, 'markdown', cellContent);
+
+  await page.menu.clickMenuItem('Help>Jupyter Reference');
+
+  await expect(
+    page
+      .frameLocator('iframe[src="https://jupyter.org/documentation"]')
+      .locator('h1')
+      .first()
+  ).toHaveText('Jupyter Project Documentation#');
+
+  await page.activity.activateTab(notebookFilename);
+
+  await page.locator('.jp-MarkdownCell .jp-InputArea-editor').waitFor();
+
+  await expect(
+    page.locator('.jp-MarkdownCell .jp-InputArea-editor')
+  ).toHaveText(`xxxxxxxxxx ${cellContent}`);
+});

packages/application-extension/schema/shell.json

@@ -5,9 +5,9 @@
     "hiddenMode": {
       "type": "string",
       "title": "Hidden mode of main panel widgets",
-      "description": "The method for hiding widgets in the main dock panel. Using `scale` will often increase performance as most browsers will not trigger style computation for the transform action.",
+      "description": "The method for hiding widgets in the main dock panel. Using `scale` will increase performance on Firefox but don't use it with Chrome, Chromium or Edge.",
       "enum": ["display", "scale"],
-      "default": "scale"
+      "default": "display"
     }
   },
   "additionalProperties": false,