[BUG] Export conflicts between `dart:ui` and `dart:ui_web` causing web build failures

[VEMUC002]

Description

The package fails to compile for Flutter web builds due to export conflicts between dart:ui and dart:ui_web. This issue occurs because both libraries are exported unconditionally in lib/utils/shims/dart_ui_real.dart, which causes namespace collisions as Flutter has migrated web-specific APIs from dart:ui to dart:ui_web.

Environment

• Package version: html_editor_enhanced: 2.7.1
• Flutter version: 3.35.3 (and likely affects other recent versions)
• Dart SDK: >=3.7.0
• Platform: Web (Flutter Web)
• Build environment: Both local and CI/CD (GitHub Actions)

Error Messages

'debugEmulateFlutterTesterEnvironment' is exported from both 'dart:ui' and 'dart:ui_web'.
'platformViewRegistry' is exported from both 'dart:ui' and 'dart:ui_web'.

Additional Error

There's also a secondary issue with deprecated API usage in lib/utils/utils.dart:

Error: The getter 'window' isn't defined for the type '_DropdownButtonState<T>'.
      final Size size = window.physicalSize;
                        ^^^^^^

Steps to Reproduce

1. Create a Flutter web project
2. Add html_editor_enhanced: ^2.7.1 as a dependency (directly or transitively via markdown_widgets)
3. Run flutter build web --release
4. Observe compilation failure

Root Cause

As of Flutter 3.x (2025-2026), Flutter has deprecated web-specific APIs in dart:ui and moved them to dart:ui_web. The current implementation in lib/utils/shims/dart_ui_real.dart exports both libraries unconditionally:

Current code (lib/utils/shims/dart_ui_real.dart):

export 'dart:ui';
export 'dart:ui_web';

This causes the symbols platformViewRegistry and debugEmulateFlutterTesterEnvironment to be exported from both libraries, creating ambiguity.

Proposed Solution

Fix 1: Update lib/utils/shims/dart_ui_real.dart to explicitly hide conflicting symbols:

// Copyright 2019 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.

// Hide deprecated symbols from dart:ui that are now in dart:ui_web
// This avoids the "exported from both" conflict
export 'dart:ui' hide platformViewRegistry, debugEmulateFlutterTesterEnvironment;
export 'dart:ui_web';

Fix 2: Update lib/utils/utils.dart to use modern Flutter API:

Add import at the top of the file:

import 'dart:ui' as ui;

Replace deprecated window.physicalSize usage (around line 1050):

// Before
final Size size = window.physicalSize;

// After
final Size size = ui.PlatformDispatcher.instance.views.first.physicalSize;

Why This Approach Works

The hide directive explicitly excludes the deprecated symbols from dart:ui, allowing dart:ui_web to provide them. This is the recommended Flutter migration pattern for handling this deprecation and:

• ✅ Directly addresses the namespace collision
• ✅ Works consistently across all platforms (web, mobile, desktop)
• ✅ Future-proof: when Flutter removes these symbols from dart:ui, the hide clause becomes harmless
• ✅ No conditional compilation needed
• ✅ Follows Flutter's deprecation migration best practices

Impact

This issue affects all users building Flutter web applications that depend on html_editor_enhanced version 2.7.1 (and likely earlier versions) with Flutter 3.x+. It completely blocks web builds.

Packages known to be affected:

• markdown_widgets (uses html_editor_enhanced as a transitive dependency)

Workaround

Until a new version is released, users can patch the package locally.

References

• Flutter documentation on platform-specific code: https://dart.dev/guides/libraries/library-tour#dartui-and-dartuiweb
• Dart conditional imports: https://dart.dev/guides/libraries/create-library-packages#conditionally-importing-and-exporting-library-files
• Related Flutter issue on dart:ui_web migration: Cleanup dart:ui shim for web-only APIs in web plugins. flutter/flutter#55000

---

Thank you for maintaining this package! I'm happy to submit a PR with these fixes if that would be helpful.

[plchekspend]

Hey @VEMUC002 Please submit a PR if you found a proper solution for this bug,
Probably author is not actively resolving the bugs