Tooltips after one second, and at once for the next button

From the development repository at b7ffe0e.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/test_end_to_end.py

@@ -880,6 +880,42 @@ class EndToEndTest(unittest.TestCase):
         firefox.switch_to(host_tab)
         firefox.go("about:blank")
 
+    def test_tooltips(self):
+        """A button's explanation appears after the pointer has been in it
+        for a second; once one is showing, a neighbour's appears at once;
+        a press ends that."""
+        firefox = self.firefox
+        firefox.go(self.address("Late"))
+        self.enter_name("Reader", "start_session")
+        self.wait_until(lambda s: s["page"]["number"] == 1, "the page")
+        hover = lambda tool: firefox.run("""
+            document.querySelector('[data-tool=' + arguments[0] + ']')
+              .dispatchEvent(new PointerEvent('pointerover', {bubbles: true, pointerType: 'pen'}));
+        """, tool)
+        showing = lambda: firefox.run("""
+            const t = document.querySelector('.tooltip');
+            return t && !t.hidden ? t.textContent.slice(0, 20) : null;
+        """)
+        hover("pen")
+        time.sleep(0.5)
+        self.assertIsNone(showing())
+        time.sleep(0.8)
+        self.assertEqual(showing(), "Write on the page. O")
+        # The neighbour rule: the next tooltip comes without the wait.
+        firefox.run("document.body.dispatchEvent(new PointerEvent('pointerover', {bubbles: true}));")
+        self.assertIsNone(showing())
+        hover("text")
+        time.sleep(0.1)
+        self.assertEqual(showing(), "Type on the page. Ta")
+        # A press ends the tooltip and the rule.
+        firefox.run("document.body.dispatchEvent(new PointerEvent('pointerdown', {bubbles: true}));")
+        self.assertIsNone(showing())
+        hover("pen")
+        time.sleep(0.5)
+        self.assertIsNone(showing())
+        time.sleep(0.8)
+        self.assertEqual(showing(), "Write on the page. O")
+
     def test_hide_rectangles(self):
         """The teacher's requests of 2026-10-08: a Hide rectangle covers part
         of the page in white for everyone, marked by blue corners."""