Add DropdownMenu cursor behavior sample (#146133)

fixes [Add `DropdownMenu` cursor behavior sample to  `DropdownMenu.enabled` & `DropdownMenu.requestFocusOnTap`  docs](https://github.com/flutter/flutter/issues/146131)

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![Screenshot 2024-04-02 at 17 12 43](https://github.com/flutter/flutter/assets/48603081/33865ca0-d48d-4651-9c83-9bdcd6369cb8)

examples/api/lib/material/dropdown_menu/dropdown_menu.2.dart

@@ -0,0 +1,169 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+/// Flutter code sample for [DropdownMenu].
+
+const List<String> list = <String>['One', 'Two', 'Three', 'Four'];
+
+void main() => runApp(const DropdownMenuApp());
+
+class DropdownMenuApp extends StatelessWidget {
+  const DropdownMenuApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(title: const Text('DropdownMenu Sample')),
+        body: const Center(
+          child: DropdownMenuExample(),
+        ),
+      ),
+    );
+  }
+}
+
+class DropdownMenuExample extends StatefulWidget {
+  const DropdownMenuExample({super.key});
+
+  @override
+  State<DropdownMenuExample> createState() => _DropdownMenuExampleState();
+}
+
+class _DropdownMenuExampleState extends State<DropdownMenuExample> {
+  String dropdownValue = list.first;
+
+  @override
+  Widget build(BuildContext context) {
+    final ColorScheme colorScheme = Theme.of(context).colorScheme;
+
+    return ListView(
+      children: <Widget>[
+        ListTile(
+          tileColor: colorScheme.primaryContainer,
+          title: const Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: <Widget>[
+              Text('enabled: true'),
+              Text('requestFocusOnTap: true'),
+            ],
+          ),
+          subtitle: Column(
+            children: <Widget>[
+              DropdownMenu<String>(
+                requestFocusOnTap: true,
+                initialSelection: list.first,
+                expandedInsets: EdgeInsets.zero,
+                onSelected: (String? value) {
+                  setState(() {
+                    dropdownValue = value!;
+                  });
+                },
+                dropdownMenuEntries:
+                    list.map<DropdownMenuEntry<String>>((String value) {
+                  return DropdownMenuEntry<String>(value: value, label: value);
+                }).toList(),
+              ),
+              const Text('Text cursor is shown when hovering over the DropdownMenu.'),
+            ],
+          ),
+        ),
+        const SizedBox(height: 20),
+        ListTile(
+          tileColor: colorScheme.primaryContainer,
+          title: const Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: <Widget>[
+              Text('enabled: true'),
+              Text('requestFocusOnTap: false'),
+            ],
+          ),
+          subtitle: Column(
+            children: <Widget>[
+              DropdownMenu<String>(
+                requestFocusOnTap: false,
+                initialSelection: list.first,
+                expandedInsets: EdgeInsets.zero,
+                onSelected: (String? value) {
+                  setState(() {
+                    dropdownValue = value!;
+                  });
+                },
+                dropdownMenuEntries:
+                    list.map<DropdownMenuEntry<String>>((String value) {
+                  return DropdownMenuEntry<String>(value: value, label: value);
+                }).toList(),
+              ),
+              const Text('Clickable cursor is shown when hovering over the DropdownMenu.'),
+            ],
+          ),
+        ),
+        const SizedBox(height: 20),
+        ListTile(
+          tileColor: colorScheme.onInverseSurface,
+          title: const Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: <Widget>[
+              Text('enabled: false'),
+              Text('requestFocusOnTap: true'),
+            ],
+          ),
+          subtitle: Column(
+            children: <Widget>[
+              DropdownMenu<String>(
+                enabled: false,
+                requestFocusOnTap: true,
+                initialSelection: list.first,
+                expandedInsets: EdgeInsets.zero,
+                onSelected: (String? value) {
+                  setState(() {
+                    dropdownValue = value!;
+                  });
+                },
+                dropdownMenuEntries:
+                    list.map<DropdownMenuEntry<String>>((String value) {
+                  return DropdownMenuEntry<String>(value: value, label: value);
+                }).toList(),
+              ),
+              const Text('Default cursor is shown when hovering over the DropdownMenu.'),
+            ],
+          ),
+        ),
+        const SizedBox(height: 20),
+        ListTile(
+          tileColor: colorScheme.onInverseSurface,
+          title: const Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: <Widget>[
+              Text('enabled: false'),
+              Text('requestFocusOnTap: false'),
+            ],
+          ),
+          subtitle: Column(
+            children: <Widget>[
+              DropdownMenu<String>(
+                enabled: false,
+                requestFocusOnTap: false,
+                initialSelection: list.first,
+                expandedInsets: EdgeInsets.zero,
+                onSelected: (String? value) {
+                  setState(() {
+                    dropdownValue = value!;
+                  });
+                },
+                dropdownMenuEntries:
+                    list.map<DropdownMenuEntry<String>>((String value) {
+                  return DropdownMenuEntry<String>(value: value, label: value);
+                }).toList(),
+              ),
+              const Text('Default cursor is shown when hovering over the DropdownMenu.'),
+            ],
+          ),
+        ),
+      ],
+    );
+  }
+}

examples/api/test/material/dropdown_menu/dropdown_menu.2_test.dart

@@ -0,0 +1,43 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:ui';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_api_samples/material/dropdown_menu/dropdown_menu.2.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('DropdownMenu cursor behavoir', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.DropdownMenuApp(),
+    );
+
+    Finder textFieldFinder(int index) {
+      return find.byType(TextField).at(index);
+    }
+
+    // Hover over the "enabled and requestFocusOnTap set to true" text field.
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.moveTo(tester.getCenter(textFieldFinder(0)));
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+
+    // Hover over the "enabled and requestFocusOnTap set to false" text field.
+    await gesture.moveTo(tester.getCenter(textFieldFinder(1)));
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+
+    // Hover over the "disabled and requestFocusOnTap set to true" text field.
+    await gesture.moveTo(tester.getCenter(textFieldFinder(2)));
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
+
+    // Hover over the "disabled and requestFocusOnTap set to false" text field.
+   await gesture.moveTo(tester.getCenter(textFieldFinder(3)));
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
+  });
+}

packages/flutter/lib/src/material/dropdown_menu.dart

@@ -170,6 +170,13 @@ class DropdownMenu<T> extends StatefulWidget {
   /// Determine if the [DropdownMenu] is enabled.
   ///
   /// Defaults to true.
+  ///
+  /// {@tool dartpad}
+  /// This sample demonstrates how the [enabled] and [requestFocusOnTap] properties
+  /// affect the textfield's hover cursor.
+  ///
+  /// ** See code in examples/api/lib/material/dropdown_menu/dropdown_menu.2.dart **
+  /// {@end-tool}
   final bool enabled;
 
   /// Determine the width of the [DropdownMenu].
@@ -338,6 +345,13 @@ class DropdownMenu<T> extends StatefulWidget {
   ///    focus when activated.
   ///
   /// Set this to true or false explicitly to override the default behavior.
+  ///
+  /// {@tool dartpad}
+  /// This sample demonstrates how the [enabled] and [requestFocusOnTap] properties
+  /// affect the textfield's hover cursor.
+  ///
+  /// ** See code in examples/api/lib/material/dropdown_menu/dropdown_menu.2.dart **
+  /// {@end-tool}
   final bool? requestFocusOnTap;
 
   /// Descriptions of the menu items in the [DropdownMenu].