Create `DropdownMenu` Widget to Support Material 3 (#116088)

* Created ComboBox

* Fixed failing tests

* Reverted the menu style tests change

* Addressed comments

* Updated documentation and rename foregroundColor variable

* Remamed ComboBox to DropdownMenu

* Removed a unused import

* Removed unused import
Co-authored-by: Qun Cheng <quncheng@google.com>

examples/api/lib/material/dropdown_menu/dropdown_menu.0.dart

+// 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.
+
+/// Flutter code sample for [DropdownMenu]s. The first dropdown menu has an outlined border
+/// which is the default configuration, and the second one has a filled input decoration.
+
+import 'package:flutter/material.dart';
+
+void main() => runApp(const DropdownMenuExample());
+
+class DropdownMenuExample extends StatelessWidget {
+  const DropdownMenuExample({super.key});
+
+  List<DropdownMenuEntry> getEntryList() {
+    final List<DropdownMenuEntry> entries = <DropdownMenuEntry>[];
+
+    for (int index = 0; index < EntryLabel.values.length; index++) {
+      // Disabled item 1, 2 and 6.
+      final bool enabled = index != 1 && index != 2 && index != 6;
+      entries.add(DropdownMenuEntry(label: EntryLabel.values[index].label, enabled: enabled));
+    }
+    return entries;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final List<DropdownMenuEntry> dropdownMenuEntries = getEntryList();
+
+    return MaterialApp(
+      theme: ThemeData(
+        useMaterial3: true,
+        colorSchemeSeed: Colors.green
+      ),
+      home: Scaffold(
+        body: SafeArea(
+          child: Padding(
+            padding: const EdgeInsets.only(top: 20),
+            child: Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: <Widget>[
+                DropdownMenu(
+                  label: const Text('Label'),
+                  dropdownMenuEntries: dropdownMenuEntries,
+                ),
+                const SizedBox(width: 20),
+                DropdownMenu(
+                  enableFilter: true,
+                  leadingIcon: const Icon(Icons.search),
+                  label: const Text('Label'),
+                  dropdownMenuEntries: dropdownMenuEntries,
+                  inputDecorationTheme: const InputDecorationTheme(filled: true),
+                )
+              ],
+            ),
+          )
+        ),
+      ),
+    );
+  }
+}
+
+enum EntryLabel {
+  item0('Item 0'),
+  item1('Item 1'),
+  item2('Item 2'),
+  item3('Item 3'),
+  item4('Item 4'),
+  item5('Item 5'),
+  item6('Item 6');
+
+  const EntryLabel(this.label);
+  final String label;
+}

packages/flutter/lib/material.dart

@@ -77,6 +77,8 @@ export 'src/material/drawer.dart';
 export 'src/material/drawer_header.dart';
 export 'src/material/drawer_theme.dart';
 export 'src/material/dropdown.dart';
+export 'src/material/dropdown_menu.dart';
+export 'src/material/dropdown_menu_theme.dart';
 export 'src/material/elevated_button.dart';
 export 'src/material/elevated_button_theme.dart';
 export 'src/material/elevation_overlay.dart';

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

+// 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/cupertino.dart';
+import 'package:flutter/foundation.dart';
+
+import 'input_decorator.dart';
+import 'menu_style.dart';
+import 'theme.dart';
+
+// Examples can assume:
+// late BuildContext context;
+
+/// Overrides the default values of visual properties for descendant [DropdownMenu] widgets.
+///
+/// Descendant widgets obtain the current [DropdownMenuThemeData] object with
+/// [DropdownMenuTheme.of]. Instances of [DropdownMenuTheme] can
+/// be customized with [DropdownMenuThemeData.copyWith].
+///
+/// Typically a [DropdownMenuTheme] is specified as part of the overall [Theme] with
+/// [ThemeData.dropdownMenuTheme].
+///
+/// All [DropdownMenuThemeData] properties are null by default. When null, the [DropdownMenu]
+/// computes its own default values, typically based on the overall
+/// theme's [ThemeData.colorScheme], [ThemeData.textTheme], and [ThemeData.iconTheme].
+@immutable
+class DropdownMenuThemeData with Diagnosticable {
+  /// Creates a [DropdownMenuThemeData] that can be used to override default properties
+  /// in a [DropdownMenuTheme] widget.
+  const DropdownMenuThemeData({
+    this.textStyle,
+    this.inputDecorationTheme,
+    this.menuStyle,
+  });
+
+  /// Overrides the default value for [DropdownMenu.textStyle].
+  final TextStyle? textStyle;
+
+  /// The input decoration theme for the [TextField]s in a [DropdownMenu].
+  ///
+  /// If this is null, the [DropdownMenu] provides its own defaults.
+  final InputDecorationTheme? inputDecorationTheme;
+
+  /// Overrides the menu's default style in a [DropdownMenu].
+  ///
+  /// Any values not set in the [MenuStyle] will use the menu default for that
+  /// property.
+  final MenuStyle? menuStyle;
+
+  /// Creates a copy of this object with the given fields replaced with the
+  /// new values.
+  DropdownMenuThemeData copyWith({
+    TextStyle? textStyle,
+    InputDecorationTheme? inputDecorationTheme,
+    MenuStyle? menuStyle,
+  }) {
+    return DropdownMenuThemeData(
+      textStyle: textStyle ?? this.textStyle,
+      inputDecorationTheme: inputDecorationTheme ?? this.inputDecorationTheme,
+      menuStyle: menuStyle ?? this.menuStyle,
+    );
+  }
+
+  /// Linearly interpolates between two dropdown menu themes.
+  static DropdownMenuThemeData lerp(DropdownMenuThemeData? a, DropdownMenuThemeData? b, double t) {
+    return DropdownMenuThemeData(
+      textStyle: TextStyle.lerp(a?.textStyle, b?.textStyle, t),
+      inputDecorationTheme: t < 0.5 ? a?.inputDecorationTheme : b?.inputDecorationTheme,
+      menuStyle: MenuStyle.lerp(a?.menuStyle, b?.menuStyle, t),
+    );
+  }
+
+  @override
+  int get hashCode => Object.hash(
+    textStyle,
+    inputDecorationTheme,
+    menuStyle,
+  );
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) {
+      return true;
+    }
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is DropdownMenuThemeData
+        && other.textStyle == textStyle
+        && other.inputDecorationTheme == inputDecorationTheme
+        && other.menuStyle == menuStyle;
+  }
+
+  @override
+  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
+    super.debugFillProperties(properties);
+    properties.add(DiagnosticsProperty<TextStyle>('textStyle', textStyle, defaultValue: null));
+    properties.add(DiagnosticsProperty<InputDecorationTheme>('inputDecorationTheme', inputDecorationTheme, defaultValue: null));
+    properties.add(DiagnosticsProperty<MenuStyle>('menuStyle', menuStyle, defaultValue: null));
+  }
+}
+
+/// An inherited widget that defines the visual properties for [DropdownMenu]s in this widget's subtree.
+///
+/// Values specified here are used for [DropdownMenu] properties that are not
+/// given an explicit non-null value.
+class DropdownMenuTheme extends InheritedTheme {
+  /// Creates a [DropdownMenuTheme] that controls visual parameters for
+  /// descendant [DropdownMenu]s.
+  const DropdownMenuTheme({
+    super.key,
+    required this.data,
+    required super.child,
+  }) : assert(data != null);
+
+  /// Specifies the visual properties used by descendant [DropdownMenu]
+  /// widgets.
+  final DropdownMenuThemeData data;
+
+  /// The closest instance of this class that encloses the given context.
+  ///
+  /// If there is no enclosing [DropdownMenuTheme] widget, then
+  /// [ThemeData.dropdownMenuTheme] is used.
+  ///
+  /// Typical usage is as follows:
+  ///
+  /// ```dart
+  /// DropdownMenuThemeData theme = DropdownMenuTheme.of(context);
+  /// ```
+  ///
+  /// See also:
+  ///
+  ///  * [maybeOf], which returns null if it doesn't find a
+  ///    [DropdownMenuTheme] ancestor.
+  static DropdownMenuThemeData of(BuildContext context) {
+    return maybeOf(context) ?? Theme.of(context).dropdownMenuTheme;
+  }
+
+  /// The data from the closest instance of this class that encloses the given
+  /// context, if any.
+  ///
+  /// Use this function if you want to allow situations where no
+  /// [DropdownMenuTheme] is in scope. Prefer using [DropdownMenuTheme.of]
+  /// in situations where a [DropdownMenuThemeData] is expected to be
+  /// non-null.
+  ///
+  /// If there is no [DropdownMenuTheme] in scope, then this function will
+  /// return null.
+  ///
+  /// Typical usage is as follows:
+  ///
+  /// ```dart
+  /// DropdownMenuThemeData? theme = DropdownMenuTheme.maybeOf(context);
+  /// if (theme == null) {
+  ///   // Do something else instead.
+  /// }
+  /// ```
+  ///
+  /// See also:
+  ///
+  ///  * [of], which will return [ThemeData.dropdownMenuTheme] if it doesn't
+  ///    find a [DropdownMenuTheme] ancestor, instead of returning null.
+  static DropdownMenuThemeData? maybeOf(BuildContext context) {
+    assert(context != null);
+    return context.dependOnInheritedWidgetOfExactType<DropdownMenuTheme>()?.data;
+  }
+
+  @override
+  Widget wrap(BuildContext context, Widget child) {
+    return DropdownMenuTheme(data: data, child: child);
+  }
+
+  @override
+  bool updateShouldNotify(DropdownMenuTheme oldWidget) => data != oldWidget.data;
+}

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

@@ -131,6 +131,7 @@ class MenuAnchor extends StatefulWidget {
     this.anchorTapClosesMenu = false,
     this.onOpen,
     this.onClose,
+    this.crossAxisUnconstrained = true,
     required this.menuChildren,
     this.builder,
     this.child,
@@ -213,6 +214,14 @@ class MenuAnchor extends StatefulWidget {
   /// A callback that is invoked when the menu is closed.
   final VoidCallback? onClose;
 
+  /// Determine if the menu panel can be wrapped by a [UnconstrainedBox] which allows
+  /// the panel to render at its "natural" size.
+  ///
+  /// Defaults to true as it allows developers to render the menu panel at the
+  /// size it should be. When it is set to false, it can be useful when the menu should
+  /// be constrained in both main axis and cross axis, such as a [DropdownMenu].
+  final bool crossAxisUnconstrained;
+
   /// A list of children containing the menu items that are the contents of the
   /// menu surrounded by this [MenuAnchor].
   ///
@@ -516,6 +525,7 @@ class _MenuAnchorState extends State<MenuAnchor> {
                     menuPosition: position,
                     clipBehavior: widget.clipBehavior,
                     menuChildren: widget.menuChildren,
+                    crossAxisUnconstrained: widget.crossAxisUnconstrained,
                   ),
                 ),
                 to: overlay.context,
@@ -791,6 +801,7 @@ class MenuItemButton extends StatefulWidget {
     super.key,
     this.onPressed,
     this.onHover,
+    this.requestFocusOnHover = true,
     this.onFocusChange,
     this.focusNode,
     this.shortcut,
@@ -817,6 +828,11 @@ class MenuItemButton extends StatefulWidget {
   /// area and false if a pointer has exited.
   final ValueChanged<bool>? onHover;
 
+  /// Determine if hovering can request focus.
+  ///
+  /// Defaults to true.
+  final bool requestFocusOnHover;
+
   /// Handler called when the focus changes.
   ///
   /// Called with true if this widget's node gains focus, and false if it loses
@@ -1064,7 +1080,7 @@ class _MenuItemButtonState extends State<MenuItemButton> {
 
   void _handleHover(bool hovering) {
     widget.onHover?.call(hovering);
-    if (hovering) {
+    if (hovering && widget.requestFocusOnHover) {
       assert(_debugMenuInfo('Requesting focus for $_focusNode from hover'));
       _focusNode.requestFocus();
     }
@@ -2424,7 +2440,10 @@ class _MenuDirectionalFocusAction extends DirectionalFocusAction {
     // correct node.
     if (currentMenu.widget.childFocusNode != null) {
       final FocusTraversalPolicy? policy = FocusTraversalGroup.maybeOf(primaryFocus!.context!);
-      policy?.invalidateScopeData(currentMenu.widget.childFocusNode!.nearestScope!);
+      if (currentMenu.widget.childFocusNode!.nearestScope != null) {
+        policy?.invalidateScopeData(currentMenu.widget.childFocusNode!.nearestScope!);
+      }
+      return false;
     }
     return false;
   }
@@ -2455,7 +2474,10 @@ class _MenuDirectionalFocusAction extends DirectionalFocusAction {
     // correct node.
     if (currentMenu.widget.childFocusNode != null) {
       final FocusTraversalPolicy? policy = FocusTraversalGroup.maybeOf(primaryFocus!.context!);
-      policy?.invalidateScopeData(currentMenu.widget.childFocusNode!.nearestScope!);
+      if (currentMenu.widget.childFocusNode!.nearestScope != null) {
+        policy?.invalidateScopeData(currentMenu.widget.childFocusNode!.nearestScope!);
+      }
+      return false;
     }
     return false;
   }
@@ -3198,6 +3220,7 @@ class _MenuPanel extends StatefulWidget {
     required this.menuStyle,
     this.clipBehavior = Clip.none,
     required this.orientation,
+    this.crossAxisUnconstrained = true,
     required this.children,
   });
 
@@ -3209,6 +3232,13 @@ class _MenuPanel extends StatefulWidget {
   /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
+  /// Determine if a [UnconstrainedBox] can be applied to the menu panel to allow it to render
+  /// at its "natural" size.
+  ///
+  /// Defaults to true. When it is set to false, it can be useful when the menu should
+  /// be constrained in both main-axis and cross-axis, such as a [DropdownMenu].
+  final bool crossAxisUnconstrained;
+
   /// The layout orientation of this panel.
   final Axis orientation;
 
@@ -3297,38 +3327,45 @@ class _MenuPanelState extends State<_MenuPanel> {
         );
       }
     }
-    return ConstrainedBox(
-      constraints: effectiveConstraints,
-      child: UnconstrainedBox(
-        constrainedAxis: widget.orientation,
+
+    Widget menuPanel = _intrinsicCrossSize(
+      child: Material(
+        elevation: elevation,
+        shape: shape,
+        color: backgroundColor,
+        shadowColor: shadowColor,
+        surfaceTintColor: surfaceTintColor,
+        type: backgroundColor == null ? MaterialType.transparency : MaterialType.canvas,
         clipBehavior: Clip.hardEdge,
-        alignment: AlignmentDirectional.centerStart,
-        child: _intrinsicCrossSize(
-          child: Material(
-            elevation: elevation,
-            shape: shape,
-            color: backgroundColor,
-            shadowColor: shadowColor,
-            surfaceTintColor: surfaceTintColor,
-            type: backgroundColor == null ? MaterialType.transparency : MaterialType.canvas,
-            clipBehavior: Clip.hardEdge,
-            child: Padding(
-              padding: resolvedPadding,
-              child: SingleChildScrollView(
-                scrollDirection: widget.orientation,
-                child: Flex(
-                  crossAxisAlignment: CrossAxisAlignment.start,
-                  textDirection: Directionality.of(context),
-                  direction: widget.orientation,
-                  mainAxisSize: MainAxisSize.min,
-                  children: widget.children,
-                ),
-              ),
+        child: Padding(
+          padding: resolvedPadding,
+          child: SingleChildScrollView(
+            scrollDirection: widget.orientation,
+            child: Flex(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              textDirection: Directionality.of(context),
+              direction: widget.orientation,
+              mainAxisSize: MainAxisSize.min,
+              children: widget.children,
             ),
           ),
         ),
       ),
     );
+
+    if (widget.crossAxisUnconstrained) {
+      menuPanel = UnconstrainedBox(
+        constrainedAxis: widget.orientation,
+        clipBehavior: Clip.hardEdge,
+        alignment: AlignmentDirectional.centerStart,
+        child: menuPanel,
+      );
+    }
+
+    return ConstrainedBox(
+      constraints: effectiveConstraints,
+      child: menuPanel,
+    );
   }
 
   Widget _intrinsicCrossSize({required Widget child}) {
@@ -3349,6 +3386,7 @@ class _Submenu extends StatelessWidget {
     required this.menuPosition,
     required this.alignmentOffset,
     required this.clipBehavior,
+    this.crossAxisUnconstrained = true,
     required this.menuChildren,
   });
 
@@ -3357,6 +3395,7 @@ class _Submenu extends StatelessWidget {
   final Offset? menuPosition;
   final Offset alignmentOffset;
   final Clip clipBehavior;
+  final bool crossAxisUnconstrained;
   final List<Widget> menuChildren;
 
   @override
@@ -3454,6 +3493,7 @@ class _Submenu extends StatelessWidget {
                         menuStyle: menuStyle,
                         clipBehavior: clipBehavior,
                         orientation: anchor._orientation,
+                        crossAxisUnconstrained: crossAxisUnconstrained,
                         children: menuChildren,
                       ),
                     ),

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

@@ -25,6 +25,7 @@ import 'data_table_theme.dart';
 import 'dialog_theme.dart';
 import 'divider_theme.dart';
 import 'drawer_theme.dart';
+import 'dropdown_menu_theme.dart';
 import 'elevated_button_theme.dart';
 import 'expansion_tile_theme.dart';
 import 'filled_button_theme.dart';
@@ -348,6 +349,7 @@ class ThemeData with Diagnosticable {
     DialogTheme? dialogTheme,
     DividerThemeData? dividerTheme,
     DrawerThemeData? drawerTheme,
+    DropdownMenuThemeData? dropdownMenuTheme,
     ElevatedButtonThemeData? elevatedButtonTheme,
     ExpansionTileThemeData? expansionTileTheme,
     FilledButtonThemeData? filledButtonTheme,
@@ -602,6 +604,7 @@ class ThemeData with Diagnosticable {
     dialogTheme ??= const DialogTheme();
     dividerTheme ??= const DividerThemeData();
     drawerTheme ??= const DrawerThemeData();
+    dropdownMenuTheme ??= const DropdownMenuThemeData();
     elevatedButtonTheme ??= const ElevatedButtonThemeData();
     expansionTileTheme ??= const ExpansionTileThemeData();
     filledButtonTheme ??= const FilledButtonThemeData();
@@ -699,6 +702,7 @@ class ThemeData with Diagnosticable {
       dialogTheme: dialogTheme,
       dividerTheme: dividerTheme,
       drawerTheme: drawerTheme,
+      dropdownMenuTheme: dropdownMenuTheme,
       elevatedButtonTheme: elevatedButtonTheme,
       expansionTileTheme: expansionTileTheme,
       filledButtonTheme: filledButtonTheme,
@@ -812,6 +816,7 @@ class ThemeData with Diagnosticable {
     required this.dialogTheme,
     required this.dividerTheme,
     required this.drawerTheme,
+    required this.dropdownMenuTheme,
     required this.elevatedButtonTheme,
     required this.expansionTileTheme,
     required this.filledButtonTheme,
@@ -983,6 +988,7 @@ class ThemeData with Diagnosticable {
        assert(dialogTheme != null),
        assert(dividerTheme != null),
        assert(drawerTheme != null),
+       assert(dropdownMenuTheme != null),
        assert(elevatedButtonTheme != null),
        assert(expansionTileTheme != null),
        assert(filledButtonTheme != null),
@@ -1554,6 +1560,9 @@ class ThemeData with Diagnosticable {
   /// A theme for customizing the appearance and layout of [Drawer] widgets.
   final DrawerThemeData drawerTheme;
 
+  /// A theme for customizing the appearance and layout of [DropdownMenu] widgets.
+  final DropdownMenuThemeData dropdownMenuTheme;
+
   /// A theme for customizing the appearance and internal layout of
   /// [ElevatedButton]s.
   final ElevatedButtonThemeData elevatedButtonTheme;
@@ -1816,6 +1825,13 @@ class ThemeData with Diagnosticable {
   Color get toggleableActiveColor => _toggleableActiveColor!;
   final Color? _toggleableActiveColor;
 
+  // The number 5 was chosen without any real science or research behind it. It
+
+  // copies of ThemeData in memory comfortably) and not too small (most apps
+  // shouldn't have more than 5 theme/localization pairs).
+  static const int _localizedThemeDataCacheSize = 5;
+  /// Caches localized themes to speed up the [localize] method.
+
   /// Creates a copy of this theme but with the given fields replaced with the new values.
   ///
   /// The [brightness] value is applied to the [colorScheme].
@@ -1883,6 +1899,7 @@ class ThemeData with Diagnosticable {
     DialogTheme? dialogTheme,
     DividerThemeData? dividerTheme,
     DrawerThemeData? drawerTheme,
+    DropdownMenuThemeData? dropdownMenuTheme,
     ElevatedButtonThemeData? elevatedButtonTheme,
     ExpansionTileThemeData? expansionTileTheme,
     FilledButtonThemeData? filledButtonTheme,
@@ -2047,6 +2064,7 @@ class ThemeData with Diagnosticable {
       dialogTheme: dialogTheme ?? this.dialogTheme,
       dividerTheme: dividerTheme ?? this.dividerTheme,
       drawerTheme: drawerTheme ?? this.drawerTheme,
+      dropdownMenuTheme: dropdownMenuTheme ?? this.dropdownMenuTheme,
       elevatedButtonTheme: elevatedButtonTheme ?? this.elevatedButtonTheme,
       expansionTileTheme: expansionTileTheme ?? this.expansionTileTheme,
       filledButtonTheme: filledButtonTheme ?? this.filledButtonTheme,
@@ -2089,14 +2107,7 @@ class ThemeData with Diagnosticable {
       bottomAppBarColor: bottomAppBarColor ?? _bottomAppBarColor,
     );
   }
-
-  // The number 5 was chosen without any real science or research behind it. It
   // just seemed like a number that's not too big (we should be able to fit 5
-  // copies of ThemeData in memory comfortably) and not too small (most apps
-  // shouldn't have more than 5 theme/localization pairs).
-  static const int _localizedThemeDataCacheSize = 5;
-
-  /// Caches localized themes to speed up the [localize] method.
   static final _FifoCache<_IdentityThemeDataCacheKey, ThemeData> _localizedThemeDataCache =
       _FifoCache<_IdentityThemeDataCacheKey, ThemeData>(_localizedThemeDataCacheSize);
 
@@ -2253,6 +2264,7 @@ class ThemeData with Diagnosticable {
       dialogTheme: DialogTheme.lerp(a.dialogTheme, b.dialogTheme, t),
       dividerTheme: DividerThemeData.lerp(a.dividerTheme, b.dividerTheme, t),
       drawerTheme: DrawerThemeData.lerp(a.drawerTheme, b.drawerTheme, t)!,
+      dropdownMenuTheme: DropdownMenuThemeData.lerp(a.dropdownMenuTheme, b.dropdownMenuTheme, t),
       elevatedButtonTheme: ElevatedButtonThemeData.lerp(a.elevatedButtonTheme, b.elevatedButtonTheme, t)!,
       expansionTileTheme: ExpansionTileThemeData.lerp(a.expansionTileTheme, b.expansionTileTheme, t)!,
       filledButtonTheme: FilledButtonThemeData.lerp(a.filledButtonTheme, b.filledButtonTheme, t)!,
@@ -2361,6 +2373,7 @@ class ThemeData with Diagnosticable {
         other.dialogTheme == dialogTheme &&
         other.dividerTheme == dividerTheme &&
         other.drawerTheme == drawerTheme &&
+        other.dropdownMenuTheme == dropdownMenuTheme &&
         other.elevatedButtonTheme == elevatedButtonTheme &&
         other.expansionTileTheme == expansionTileTheme &&
         other.filledButtonTheme == filledButtonTheme &&
@@ -2466,6 +2479,7 @@ class ThemeData with Diagnosticable {
       dialogTheme,
       dividerTheme,
       drawerTheme,
+      dropdownMenuTheme,
       elevatedButtonTheme,
       expansionTileTheme,
       filledButtonTheme,
@@ -2573,6 +2587,7 @@ class ThemeData with Diagnosticable {
     properties.add(DiagnosticsProperty<DialogTheme>('dialogTheme', dialogTheme, defaultValue: defaultData.dialogTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<DividerThemeData>('dividerTheme', dividerTheme, defaultValue: defaultData.dividerTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<DrawerThemeData>('drawerTheme', drawerTheme, defaultValue: defaultData.drawerTheme, level: DiagnosticLevel.debug));
+    properties.add(DiagnosticsProperty<DropdownMenuThemeData>('dropdownMenuTheme', dropdownMenuTheme, defaultValue: defaultData.dropdownMenuTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<ElevatedButtonThemeData>('elevatedButtonTheme', elevatedButtonTheme, defaultValue: defaultData.elevatedButtonTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<ExpansionTileThemeData>('expansionTileTheme', expansionTileTheme, level: DiagnosticLevel.debug));
     properties.add(DiagnosticsProperty<FilledButtonThemeData>('filledButtonTheme', filledButtonTheme, defaultValue: defaultData.filledButtonTheme, level: DiagnosticLevel.debug));

packages/flutter/test/material/theme_data_test.dart

@@ -784,6 +784,7 @@ void main() {
       dialogTheme: const DialogTheme(backgroundColor: Colors.black),
       dividerTheme: const DividerThemeData(color: Colors.black),
       drawerTheme: const DrawerThemeData(),
+      dropdownMenuTheme: const DropdownMenuThemeData(),
       elevatedButtonTheme: ElevatedButtonThemeData(style: ElevatedButton.styleFrom(backgroundColor: Colors.green)),
       expansionTileTheme: const ExpansionTileThemeData(backgroundColor: Colors.black),
       filledButtonTheme: FilledButtonThemeData(style: FilledButton.styleFrom(foregroundColor: Colors.green)),
@@ -904,6 +905,7 @@ void main() {
       dialogTheme: const DialogTheme(backgroundColor: Colors.white),
       dividerTheme: const DividerThemeData(color: Colors.white),
       drawerTheme: const DrawerThemeData(),
+      dropdownMenuTheme: const DropdownMenuThemeData(),
       elevatedButtonTheme: const ElevatedButtonThemeData(),
       expansionTileTheme: const ExpansionTileThemeData(backgroundColor: Colors.black),
       filledButtonTheme: const FilledButtonThemeData(),
@@ -1253,6 +1255,7 @@ void main() {
       'dialogTheme',
       'dividerTheme',
       'drawerTheme',
+      'dropdownMenuTheme',
       'elevatedButtonTheme',
       'expansionTileTheme',
       'filledButtonTheme',