Add additional focus samples. (#50846)

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

@@ -62,6 +62,54 @@ export 'package:flutter/services.dart' show SmartQuotesType, SmartDashesType;
 /// ```
 /// {@end-tool}
 ///
+/// {@tool dartpad --template=stateful_widget_material}
+/// This example shows how to move the focus to the next field when the user
+/// presses the ENTER key.
+///
+/// ```dart imports
+/// import 'package:flutter/services.dart';
+/// ```
+///
+/// ```dart
+/// Widget build(BuildContext context) {
+///   return Material(
+///     child: Center(
+///       child: Shortcuts(
+///         shortcuts: <LogicalKeySet, Intent>{
+///           // Pressing enter on the field will now move to the next field.
+///           LogicalKeySet(LogicalKeyboardKey.enter):
+///               Intent(NextFocusAction.key),
+///         },
+///         child: FocusTraversalGroup(
+///           child: Form(
+///             autovalidate: true,
+///             onChanged: () {
+///               Form.of(primaryFocus.context).save();
+///             },
+///             child: Wrap(
+///               children: List<Widget>.generate(5, (int index) {
+///                 return Padding(
+///                   padding: const EdgeInsets.all(8.0),
+///                   child: ConstrainedBox(
+///                     constraints: BoxConstraints.tight(Size(200, 50)),
+///                     child: TextFormField(
+///                       onSaved: (String value) {
+///                         print('Value for field $index saved as "$value"');
+///                       },
+///                     ),
+///                   ),
+///                 );
+///               }),
+///             ),
+///           ),
+///         ),
+///       ),
+///     ),
+///   );
+/// }
+/// ```
+/// {@end-tool}
+///
 /// See also:
 ///
 ///  * <https://material.io/design/components/text-fields.html>

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

@@ -374,12 +374,14 @@ class Actions extends InheritedWidget {
 /// {@tool dartpad --template=stateful_widget_material}
 /// This example shows how keyboard interaction can be added to a custom control
 /// that changes color when hovered and focused, and can toggle a light when
-/// activated, either by touch or by hitting the `X` key on the keyboard.
+/// activated, either by touch or by hitting the `X` key on the keyboard when
+/// the "And Me" button has the keyboard focus (be sure to use TAB to move the
+/// focus to the "And Me" button before trying it out).
 ///
 /// This example defines its own key binding for the `X` key, but in this case,
 /// there is also a default key binding for [ActivateAction] in the default key
 /// bindings created by [WidgetsApp] (the parent for [MaterialApp], and
-/// [CupertinoApp]), so the `ENTER` key will also activate the control.
+/// [CupertinoApp]), so the `ENTER` key will also activate the buttons.
 ///
 /// ```dart imports
 /// import 'package:flutter/services.dart';

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

@@ -951,8 +951,8 @@ class _ReadingOrderDirectionalGroupData extends Diagnosticable {
 /// 3. Pick the closest to the beginning of the reading order from among the
 ///    nodes discovered above.
 ///
-/// It uses the ambient [Directionality] in the context for the enclosing scope
-/// to determine which direction is "reading order".
+/// It uses the ambient [Directionality] in the context for the enclosing
+/// [FocusTraversalGroup] to determine which direction is "reading order".
 ///
 /// See also:
 ///
@@ -1296,11 +1296,14 @@ class _OrderedFocusInfo {
 ///     ),
 ///   );
 /// }
+/// ```
 /// {@end-tool}
 ///
 /// See also:
 ///
-///  * [WidgetOrderFocusTraversalPolicy], a policy that relies on the widget
+///  * [FocusTraversalGroup], a widget that groups together and imposes a
+///    traversal policy on the [Focus] nodes below it in the widget hierarchy.
+///  * [WidgetOrderTraversalPolicy], a policy that relies on the widget
 ///    creation order to describe the order of traversal.
 ///  * [ReadingOrderTraversalPolicy], a policy that describes the order as the
 ///    natural "reading order" for the current [Directionality].