Add focus fix

pkgs/dartpad_ui/lib/blur.dart

@@ -0,0 +1,30 @@
+// Copyright 2025 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file or at https://developers.google.com/open-source/licenses/bsd.
+
+import 'dart:js_interop';
+
+import 'package:web/web.dart';
+
+const _flutterViewSelector = 'flutter-view';
+
+void addBlurListener() {
+  window.addEventListener('blur', _onBlur.toJS);
+}
+
+void removeBlurListener() {
+  window.removeEventListener('blur', _onBlur.toJS);
+}
+
+void _onBlur(Event _) {
+  print('onBlur');
+  final activeElement = document.activeElement as HTMLElement?;
+  if (activeElement == null) return;
+  // Only call blur on elements that are within a Flutter view.
+  final inFlutterView = activeElement.closest(_flutterViewSelector) != null;
+  print('inFlutterView = $inFlutterView');
+  if (inFlutterView) {
+    print('activeElement = $activeElement');
+    activeElement.blur();
+  }
+}

pkgs/dartpad_ui/lib/main.dart

@@ -16,6 +16,7 @@ import 'package:split_view/split_view.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
 import 'package:vtable/vtable.dart';
 
+import 'blur.dart';
 import 'console.dart';
 import 'embed.dart';
 import 'enable_gen_ai.dart';
@@ -301,6 +302,9 @@ class _DartPadMainPageState extends State<DartPadMainPage>
           if (widget.runOnLoad) {
             appServices.performCompileAndRun();
           }
+        })
+        .then((_) {
+          addBlurListener();
         });
     appModel.compilingState.addListener(_handleRunStarted);
 

pkgs/dartpad_ui/web/frame.js

@@ -65,3 +65,34 @@ window.addEventListener('load', function () {
   window.addEventListener('message', messageHandler, false);
   parent.postMessage({ 'sender': 'frame', 'type': 'ready' }, '*');
 });
+
+window.addEventListener('blur', onBlurHandler);
+
+// Blur listener
+const flutterViewSelector = 'flutter-view';
+function onBlurHandler(event) {
+  console.log('onBlur');
+  const activeElement = document.activeElement;
+  if (!activeElement) {
+    return;
+  }
+  if (!(activeElement instanceof HTMLElement) || typeof activeElement.closest !== 'function') {
+    return;
+  }
+  const inFlutterView = activeElement.closest(flutterViewSelector) !== null;
+  console.log(`JS inFlutterView = ${inFlutterView}`);
+
+  if (inFlutterView) {
+    console.log('JS activeElement = ', activeElement);
+    activeElement.blur();
+  }
+}
+
+function addBlurListener() {
+  window.addEventListener('blur', onBlurHandler);
+  console.log('JS Blur listener added.');
+}
+function removeBlurListener() {
+  window.removeEventListener('blur', onBlurHandler);
+  console.log('JS Blur listener removed.');
+}