Fix default overlay color in `TabBar` #175270

ValentinVignal · 2025-09-12T17:09:41Z

Fix the TODO introduced in #174746 (comment)

The hidden bug was that the incorrect color was used for the overlay color of TabBar when using the default theme:

Consider the scenario for a selected tab:

The user over it
The user presses it
The user stops the press and hovers it again

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

Lines 2698 to 2723 in 2efda9c

    
           WidgetStateProperty<Color?> get overlayColor { 
        
             return WidgetStateProperty.resolveWith((Set<WidgetState> states) { 
        
               if (states.contains(WidgetState.selected)) { 
        
                 if (states.contains(WidgetState.pressed)) { 
        
                   return _colors.primary.withOpacity(0.1); 
        
                 } 
        
                 if (states.contains(WidgetState.hovered)) { 
        
                   return _colors.primary.withOpacity(0.08); 
        
                 } 
        
                 if (states.contains(WidgetState.focused)) { 
        
                   return _colors.primary.withOpacity(0.1); 
        
                 } 
        
                 return null; 
        
               } 
        
               if (states.contains(WidgetState.pressed)) { 
        
                 return _colors.primary.withOpacity(0.1); 
        
               } 
        
               if (states.contains(WidgetState.hovered)) { 
        
                 return _colors.onSurface.withOpacity(0.08); 
        
               } 
        
               if (states.contains(WidgetState.focused)) { 
        
                 return _colors.onSurface.withOpacity(0.1); 
        
               } 
        
               return null; 
        
             }); 
        
           }

Since the hovered and pressed colors are very similar, it is hard to catch. I've made a video to illustrate it when the hovered color is blue 🟦 and the pressed color is red 🟥:

	Before	After
Overlay color	1. `primary.withOpacity(0.08)` 2. `primary.withOpacity(0.1)` 3. `primary.withOpacity(0.1)` ❌ Wrong color	1. `primary.withOpacity(0.08)` 2. `primary.withOpacity(0.1)` 3. `primary.withOpacity(0.08)` ✅ Correct color
	Screen.Recording.2025-09-13.at.1.23.58.AM.mov	Screen.Recording.2025-09-13.at.1.23.09.AM.mov

	Before	After
overlay color	1. `primary.withOpacity(0.08)`

`` | 1. primary.withOpacity(0.08) |

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
I followed the breaking change policy and added Data Driven Fixes where supported.
All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

Note: The Flutter team is currently trialing the use of Gemini Code Assist for GitHub. Comments from the gemini-code-assist bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.

gemini-code-assist

Code Review

This pull request correctly addresses a bug in the TabBar widget where mutating a Set within the build method led to incorrect overlay colors. The change to create a new set using .toSet() before modification is the proper way to handle state immutability within build methods, preventing side effects on subsequent rebuilds. The accompanying test case is well-crafted, specifically targeting the scenario that would have previously failed, thereby ensuring the fix is effective and guarding against regressions. The changes are clean, correct, and improve the overall robustness of the widget.

chunhtai

Do you think it is possible to repro a bug based on the code?

chunhtai · 2025-09-12T17:58:42Z

packages/flutter/test/material/tabs_test.dart

    await tester.pumpAndSettle();
    expect(overlayColor(), paints..rect(color: theme.colorScheme.onSurface.withOpacity(0.08)));

+    await gesture.moveTo(tester.getCenter(find.text(selectedValue)));


What is this for this additional operation test for?

This is to make the test failing without the code change.

Before the code change, expect(overlayColor(), paints..rect(color: theme.colorScheme.primary.withOpacity(0.08))); would fail (the color of the overlay was theme.colorScheme.primary.withOpacity(0.1)

Would you prefer me to write a new test, or add a comment or something?

oh it is fine then, LGTM

ValentinVignal · 2025-09-13T05:47:49Z

Do you think it is possible to repro a bug based on the code?

Yes, I could reproduce a bug, I described it in the description. Or are there some unclear details you need to me explain?

chunhtai

LGTM

chunhtai · 2025-09-15T21:42:29Z

packages/flutter/test/material/tabs_test.dart

    await tester.pumpAndSettle();
    expect(overlayColor(), paints..rect(color: theme.colorScheme.onSurface.withOpacity(0.08)));

+    await gesture.moveTo(tester.getCenter(find.text(selectedValue)));


oh it is fine then, LGTM

flutter/flutter@29a238d...8d0b31d 2025-09-16 [email protected] Roll Packages from fcd5f68 to 0255ac9 (2 revisions) (flutter/flutter#175427) 2025-09-16 [email protected] Adds a11y section locale support for iOS (flutter/flutter#175005) 2025-09-16 [email protected] Roll Skia from 4e9c86d4a6d9 to 7d160bbf9403 (3 revisions) (flutter/flutter#175404) 2025-09-16 [email protected] [native_assets] Find more `CCompilerConfig` on Linux (flutter/flutter#175323) 2025-09-16 [email protected] Roll Dart SDK from 50e61e5bff51 to 700de52f29a9 (3 revisions) (flutter/flutter#175395) 2025-09-16 [email protected] Fix default overlay color in `TabBar` (flutter/flutter#175270) 2025-09-16 [email protected] Migrate to widget state (flutter/flutter#175242) 2025-09-16 [email protected] Roll Skia from 01b0ede33ae9 to 4e9c86d4a6d9 (1 revision) (flutter/flutter#175387) 2025-09-15 [email protected] Merge the engine README into the README of the old buildroot. (flutter/flutter#175384) 2025-09-15 [email protected] Marks Mac_ios microbenchmarks_ios to be unflaky (flutter/flutter#171146) 2025-09-15 [email protected] Deprecate Objective-C plugin template (flutter/flutter#174003) 2025-09-15 [email protected] Add a gn --ccache argument (flutter/flutter#174621) 2025-09-15 [email protected] Update `build.gradle` to remove deprecation warning in `flutter\engine\src\flutter\shell\platform\android` (flutter/flutter#175305) 2025-09-15 [email protected] Show cursor after swipe only if TextField has focus (flutter/flutter#175044) 2025-09-15 [email protected] Roll Skia from f950263bb3d4 to 01b0ede33ae9 (7 revisions) (flutter/flutter#175373) 2025-09-15 [email protected] Update Chromium sysroot to pick up RISC-V support. (flutter/flutter#173671) 2025-09-15 [email protected] Set Gemini Code Assist `include_drafts` to false (flutter/flutter#175098) 2025-09-15 [email protected] Roll Packages from 15e7e89 to fcd5f68 (3 revisions) (flutter/flutter#175366) 2025-09-15 [email protected] Remove 'v' Open DevTools from help on web in profile/release mode (flutter/flutter#172829) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Fix the TODO introduced in flutter#174746 (comment) The hidden bug was that the incorrect color was used for the overlay color of `TabBar` when using the default theme: Consider the scenario for a selected tab: 1. The user over it 2. The user presses it 3. The user stops the press and hovers it again https://github.com/flutter/flutter/blob/2efda9cc146fa6eef5f758511cf04a55635366cb/packages/flutter/lib/src/material/tabs.dart#L2698-L2723 Since the hovered and pressed colors are very similar, it is hard to catch. I've made a video to illustrate it when the hovered color is blue 🟦 and the pressed color is red 🟥: <table> <tr> <th></th> <th>Before</th> <th>After</th> </tr> <tr> <td>Overlay color</td> <td> 1. <code>primary.withOpacity(0.08)</code><br/> 2. <code>primary.withOpacity(0.1)</code><br/> 3. <code>primary.withOpacity(0.1)</code> ❌ Wrong color </td> <td> 1. <code>primary.withOpacity(0.08)</code><br/> 2. <code>primary.withOpacity(0.1)</code><br/> 3. <code>primary.withOpacity(0.08)</code> ✅ Correct color </td> </tr> <tr> <td></td> <td> https://github.com/user-attachments/assets/667ea9b9-dce1-446b-93ae-68114464d518 </td> <td> https://github.com/user-attachments/assets/e0910b73-11cc-4fc2-982a-e32a7f47dd1b </td> </tr> </table> | | Before | After | | :---: | :---: | :---: | | overlay color| 1. `primary.withOpacity(0.08)` 5. `` | 1. `primary.withOpacity(0.08)` | ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [ ] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

ValentinVignal added 2 commits September 13, 2025 01:07

Do not mutate set

02b1af0

Update the tests

ae5fa60

github-actions bot added framework flutter/packages/flutter repository. See also f: labels. f: material design flutter/packages/flutter/material repository. labels Sep 12, 2025

ValentinVignal requested a review from chunhtai September 12, 2025 17:10

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ValentinVignal changed the title ~~Flutter/do not mutate set in build method~~ Fix default overlay color in TabBar Sep 12, 2025

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ValentinVignal requested a review from chunhtai September 13, 2025 05:48

chunhtai approved these changes Sep 15, 2025

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Merged via the queue into flutter:master with commit be522c6 Sep 16, 2025
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Roll Flutter from 29a238d0d506 to 2cda3fb6cdd7 (17 revisions) flutter/packages#10017

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be522c684 Fix default overlay color in TabBar (flutter/flutter#175270)

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Roll Flutter from 29a238d0d506 to e8bef9805194 (18 revisions) flutter/packages#10018

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be522c684 Fix default overlay color in TabBar (flutter/flutter#175270)

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be522c684 Fix default overlay color in TabBar (flutter/flutter#175270)

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be522c684 Fix default overlay color in TabBar (flutter/flutter#175270)

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	WidgetStateProperty<Color?> get overlayColor {
	return WidgetStateProperty.resolveWith((Set<WidgetState> states) {
	if (states.contains(WidgetState.selected)) {
	if (states.contains(WidgetState.pressed)) {
	return _colors.primary.withOpacity(0.1);
	}
	if (states.contains(WidgetState.hovered)) {
	return _colors.primary.withOpacity(0.08);
	}
	if (states.contains(WidgetState.focused)) {
	return _colors.primary.withOpacity(0.1);
	}
	return null;
	}
	if (states.contains(WidgetState.pressed)) {
	return _colors.primary.withOpacity(0.1);
	}
	if (states.contains(WidgetState.hovered)) {
	return _colors.onSurface.withOpacity(0.08);
	}
	if (states.contains(WidgetState.focused)) {
	return _colors.onSurface.withOpacity(0.1);
	}
	return null;
	});
	}

Fix default overlay color in TabBar #175270

Fix default overlay color in TabBar #175270

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Fix default overlay color in `TabBar` #175270

Fix default overlay color in `TabBar` #175270

ValentinVignal commented Sep 12, 2025 •

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