Make selectable text mouse cursor configurable (#125133)

## Description

This PR introduces `DefaultSelectionStyle.mouseCursor` to configure the mouse cursor over selectable text.
It also applies this solution to `InkResponse` to make the mouse cursor win over the default one provided by selectable `Text` for many Material components (such as buttons). 

### Before

https://user-images.githubusercontent.com/840911/233627729-ddf98e2a-444d-4c6d-a6d5-f521982f48dd.mov

### After

https://user-images.githubusercontent.com/840911/233627718-8871a68f-d33c-44cf-b4a1-91bb1fcdf076.mov

## Related Issue

Fixes https://github.com/flutter/flutter/issues/104595

## Tests

Adds 6 tests.

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

@@ -1310,23 +1310,26 @@ class _InkResponseState extends State<_InkResponseStateWidget>
             cursor: effectiveMouseCursor,
             onEnter: handleMouseEnter,
             onExit: handleMouseExit,
-            child: Semantics(
-              onTap: widget.excludeFromSemantics || widget.onTap == null ? null : simulateTap,
-              onLongPress: widget.excludeFromSemantics || widget.onLongPress == null ? null : simulateLongPress,
-              child: GestureDetector(
-                onTapDown: _primaryEnabled ? handleTapDown : null,
-                onTapUp: _primaryEnabled ? handleTapUp : null,
-                onTap: _primaryEnabled ? handleTap : null,
-                onTapCancel: _primaryEnabled ? handleTapCancel : null,
-                onDoubleTap: widget.onDoubleTap != null ? handleDoubleTap : null,
-                onLongPress: widget.onLongPress != null ? handleLongPress : null,
-                onSecondaryTapDown: _secondaryEnabled ? handleSecondaryTapDown : null,
-                onSecondaryTapUp: _secondaryEnabled ? handleSecondaryTapUp: null,
-                onSecondaryTap: _secondaryEnabled ? handleSecondaryTap : null,
-                onSecondaryTapCancel: _secondaryEnabled ? handleSecondaryTapCancel : null,
-                behavior: HitTestBehavior.opaque,
-                excludeFromSemantics: true,
-                child: widget.child,
+            child: DefaultSelectionStyle.merge(
+              mouseCursor: effectiveMouseCursor,
+              child: Semantics(
+                onTap: widget.excludeFromSemantics || widget.onTap == null ? null : simulateTap,
+                onLongPress: widget.excludeFromSemantics || widget.onLongPress == null ? null : simulateLongPress,
+                child: GestureDetector(
+                  onTapDown: _primaryEnabled ? handleTapDown : null,
+                  onTapUp: _primaryEnabled ? handleTapUp : null,
+                  onTap: _primaryEnabled ? handleTap : null,
+                  onTapCancel: _primaryEnabled ? handleTapCancel : null,
+                  onDoubleTap: widget.onDoubleTap != null ? handleDoubleTap : null,
+                  onLongPress: widget.onLongPress != null ? handleLongPress : null,
+                  onSecondaryTapDown: _secondaryEnabled ? handleSecondaryTapDown : null,
+                  onSecondaryTapUp: _secondaryEnabled ? handleSecondaryTapUp: null,
+                  onSecondaryTap: _secondaryEnabled ? handleSecondaryTap : null,
+                  onSecondaryTapCancel: _secondaryEnabled ? handleSecondaryTapCancel : null,
+                  behavior: HitTestBehavior.opaque,
+                  excludeFromSemantics: true,
+                  child: widget.child,
+                ),
               ),
             ),
           ),

packages/flutter/lib/src/widgets/default_selection_style.dart

@@ -2,8 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
+import 'basic.dart';
 import 'framework.dart';
 import 'inherited_theme.dart';
 
@@ -27,6 +26,7 @@ class DefaultSelectionStyle extends InheritedTheme {
     super.key,
     this.cursorColor,
     this.selectionColor,
+    this.mouseCursor,
     required super.child,
   });
 
@@ -41,8 +41,35 @@ class DefaultSelectionStyle extends InheritedTheme {
   const DefaultSelectionStyle.fallback({ super.key })
     : cursorColor = null,
       selectionColor = null,
+      mouseCursor = null,
       super(child: const _NullWidget());
 
+  /// Creates a default selection style that overrides the selection styles in
+  /// scope at this point in the widget tree.
+  ///
+  /// Any Arguments that are not null replace the corresponding properties on the
+  /// default selection style for the [BuildContext] where the widget is inserted.
+  static Widget merge({
+    Key? key,
+    Color? cursorColor,
+    Color? selectionColor,
+    MouseCursor? mouseCursor,
+    required Widget child,
+  }) {
+    return Builder(
+      builder: (BuildContext context) {
+        final DefaultSelectionStyle parent = DefaultSelectionStyle.of(context);
+        return DefaultSelectionStyle(
+          key: key,
+          cursorColor: cursorColor ?? parent.cursorColor,
+          selectionColor: selectionColor ?? parent.selectionColor,
+          mouseCursor: mouseCursor ?? parent.mouseCursor,
+          child: child,
+        );
+      },
+    );
+  }
+
   /// The default cursor and selection color (semi-transparent grey).
   ///
   /// This is the color that the [Text] widget uses when the specified selection
@@ -58,6 +85,11 @@ class DefaultSelectionStyle extends InheritedTheme {
   /// The background color of selected text.
   final Color? selectionColor;
 
+  /// The [MouseCursor] for mouse pointers hovering over selectable Text widgets.
+  ///
+  /// If this property is null, [SystemMouseCursors.text] will be used.
+  final MouseCursor? mouseCursor;
+
   /// The closest instance of this class that encloses the given context.
   ///
   /// If no such instance exists, returns an instance created by
@@ -77,6 +109,7 @@ class DefaultSelectionStyle extends InheritedTheme {
     return DefaultSelectionStyle(
       cursorColor: cursorColor,
       selectionColor: selectionColor,
+      mouseCursor: mouseCursor,
       child: child
     );
   }
@@ -84,7 +117,8 @@ class DefaultSelectionStyle extends InheritedTheme {
   @override
   bool updateShouldNotify(DefaultSelectionStyle oldWidget) {
     return cursorColor != oldWidget.cursorColor ||
-           selectionColor != oldWidget.selectionColor;
+           selectionColor != oldWidget.selectionColor ||
+           mouseCursor != oldWidget.mouseCursor;
   }
 }
 

packages/flutter/lib/src/widgets/text.dart

@@ -616,7 +616,7 @@ class Text extends StatelessWidget {
     );
     if (registrar != null) {
       result = MouseRegion(
-        cursor: SystemMouseCursors.text,
+        cursor: DefaultSelectionStyle.of(context).mouseCursor ?? SystemMouseCursors.text,
         child: result,
       );
     }

packages/flutter/test/material/elevated_button_test.dart

@@ -1608,6 +1608,29 @@ void main() {
     expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
   });
 
+  testWidgets('ElevatedButton in SelectionArea changes mouse cursor when hovered', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/104595.
+    await tester.pumpWidget(MaterialApp(
+      home: SelectionArea(
+        child: ElevatedButton(
+          style: ElevatedButton.styleFrom(
+            enabledMouseCursor: SystemMouseCursors.click,
+            disabledMouseCursor: SystemMouseCursors.grab,
+          ),
+          onPressed: () {},
+          child: const Text('button'),
+        ),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
+
   testWidgets('Ink Response shape matches Material shape', (WidgetTester tester) async {
     // This is a regression test for https://github.com/flutter/flutter/issues/91844
 

packages/flutter/test/material/filled_button_test.dart

@@ -1614,6 +1614,29 @@ void main() {
     expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
   });
 
+  testWidgets('FilledButton in SelectionArea changes mouse cursor when hovered', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/104595.
+    await tester.pumpWidget(MaterialApp(
+      home: SelectionArea(
+        child: FilledButton(
+          style: FilledButton.styleFrom(
+            enabledMouseCursor: SystemMouseCursors.click,
+            disabledMouseCursor: SystemMouseCursors.grab,
+          ),
+          onPressed: () {},
+          child: const Text('button'),
+        ),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
+
   testWidgets('Ink Response shape matches Material shape', (WidgetTester tester) async {
     Widget buildFrame({BorderSide? side}) {
       return MaterialApp(

packages/flutter/test/material/ink_well_test.dart

@@ -1020,6 +1020,27 @@ testWidgets('InkResponse radius can be updated', (WidgetTester tester) async {
     expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
   });
 
+  testWidgets('InkResponse containing selectable text changes mouse cursor when hovered', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/104595.
+    await tester.pumpWidget(MaterialApp(
+      home: SelectionArea(
+        child: Material(
+          child: InkResponse(
+            onTap: () {},
+            child: const Text('button'),
+          ),
+        ),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
+
   group('feedback', () {
     late FeedbackTester feedback;
 

packages/flutter/test/material/outlined_button_test.dart

@@ -1764,6 +1764,29 @@ void main() {
     expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
   });
 
+  testWidgets('OutlinedButton in SelectionArea changes mouse cursor when hovered', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/104595.
+    await tester.pumpWidget(MaterialApp(
+      home: SelectionArea(
+        child: OutlinedButton(
+          style: OutlinedButton.styleFrom(
+            enabledMouseCursor: SystemMouseCursors.click,
+            disabledMouseCursor: SystemMouseCursors.grab,
+          ),
+          onPressed: () {},
+          child: const Text('button'),
+        ),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
+
   testWidgets('OutlinedButton.styleFrom can be used to set foreground and background colors', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/material/text_button_test.dart

@@ -1570,6 +1570,29 @@ void main() {
     expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
   });
 
+  testWidgets('TextButton in SelectionArea changes mouse cursor when hovered', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/104595.
+    await tester.pumpWidget(MaterialApp(
+      home: SelectionArea(
+        child: TextButton(
+          style: TextButton.styleFrom(
+            enabledMouseCursor: SystemMouseCursors.click,
+            disabledMouseCursor: SystemMouseCursors.grab,
+          ),
+          onPressed: () {},
+          child: const Text('button'),
+        ),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
+
   testWidgets('TextButton.styleFrom can be used to set foreground and background colors', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/widgets/text_test.dart

@@ -1584,6 +1584,39 @@ void main() {
       await tester.tap(find.text('Hello World'));
       expect(tester.takeException(), isNull);
   });
+
+  testWidgets('Mouse hovering over selectable Text uses SystemMouseCursor.text', (WidgetTester tester) async {
+    await tester.pumpWidget(const MaterialApp(
+      home: SelectionArea(
+        child: Text('Flutter'),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+  });
+
+  testWidgets('Mouse hovering over selectable Text uses default selection style mouse cursor', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: SelectionArea(
+        child: DefaultSelectionStyle.merge(
+          mouseCursor: SystemMouseCursors.click,
+          child: const Text('Flutter'),
+        ),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: tester.getCenter(find.byType(Text)));
+
+    await tester.pump();
+
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
 }
 
 Future<void> _pumpTextWidget({