Add actionsOverflowAlignment parameter to dialog (#95995)

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

@@ -261,6 +261,7 @@ class AlertDialog extends StatelessWidget {
     this.actions,
     this.actionsPadding = EdgeInsets.zero,
     this.actionsAlignment,
+    this.actionsOverflowAlignment,
     this.actionsOverflowDirection,
     this.actionsOverflowButtonSpacing,
     this.buttonPadding,
@@ -375,6 +376,21 @@ class AlertDialog extends StatelessWidget {
   /// is used.
   final MainAxisAlignment? actionsAlignment;
 
+  /// The horizontal alignment of [actions] within the vertical
+  /// "overflow" layout.
+  ///
+  /// If the dialog's [actions] do not fit into a single row, then they
+  /// are arranged in a column. This parameter controls the horizontal
+  /// alignment of widgets in the case of an overflow.
+  ///
+  /// If this parameter is null (the default) then [OverflowBarAlignment.end]
+  /// is used.
+  ///
+  /// See also:
+  ///
+  /// * [OverflowBar], which [actions] configures to lay itself out.
+  final OverflowBarAlignment? actionsOverflowAlignment;
+
   /// The vertical direction of [actions] if the children overflow
   /// horizontally.
   ///
@@ -535,7 +551,7 @@ class AlertDialog extends StatelessWidget {
         child: OverflowBar(
           alignment: actionsAlignment ?? MainAxisAlignment.end,
           spacing: spacing,
-          overflowAlignment: OverflowBarAlignment.end,
+          overflowAlignment: actionsOverflowAlignment ?? OverflowBarAlignment.end,
           overflowDirection: actionsOverflowDirection ?? VerticalDirection.down,
           overflowSpacing: actionsOverflowButtonSpacing ?? 0,
           children: actions!,

packages/flutter/test/material/dialog_test.dart

@@ -1184,6 +1184,40 @@ void main() {
     expect(buttonOneRect.bottom, buttonTwoRect.top - 10.0);
   });
 
+  testWidgets('Dialogs can set the alignment of the OverflowBar', (WidgetTester tester) async {
+    final GlobalKey key1 = GlobalKey();
+    final GlobalKey key2 = GlobalKey();
+
+    final AlertDialog dialog = AlertDialog(
+      title: const Text('title'),
+      content: const Text('content'),
+      actions: <Widget>[
+        ElevatedButton(
+          key: key1,
+          onPressed: () {},
+          child: const Text('Loooooooooog button 1'),
+        ),
+        ElevatedButton(
+          key: key2,
+          onPressed: () {},
+          child: const Text('Loooooooooooooonger button 2'),
+        ),
+      ],
+      actionsOverflowAlignment: OverflowBarAlignment.center,
+    );
+
+    await tester.pumpWidget(
+      _buildAppWithDialog(dialog),
+    );
+
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    final Rect buttonOneRect = tester.getRect(find.byKey(key1));
+    final Rect buttonTwoRect = tester.getRect(find.byKey(key2));
+    expect(buttonOneRect.center.dx, buttonTwoRect.center.dx);
+  });
+
   testWidgets('Dialogs removes MediaQuery padding and view insets', (WidgetTester tester) async {
     late BuildContext outerContext;
     late BuildContext routeContext;