[Windows] FlyoutPage: Fix CollapsedPaneWidth mapping and updates

[devanathan-vaithiyanathan]

Issue Details

The CollapsedPaneWidth value was not being properly applied to the native NavigationView.

Description of Change

On Windows, FlyoutPage.CollapsedPaneWidth was not being propagated to the native RootNavigationView, so changing the attached property had no effect on CompactPaneLength.

This PR wires PlatformConfiguration.WindowsSpecific.FlyoutPage.CollapsedPaneWidthProperty into the FlyoutPage mapper and applies the value to RootNavigationView.CompactPaneLength. It also adds a property-changed callback so runtime changes call Handler.UpdateValue(...) and update the native control after the handler is created.

A Windows UI test was added to cover both the initial partial-collapse setup and a runtime width change.

Note : FlyoutPage CollapsableStyle issue was resolved in PR #29927

Issues Fixed

Fixes #33785

Tested the behavior in the following platforms.

• Android
• Windows
• iOS
• Mac

Before	After
Windows Before.mp4	Windows After.mp4

[sheiksyedm]

/azp run maui-pr-uitests 

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR fixes the FlyoutPage CollapsedPaneWidth property on Windows by implementing proper mapping from the MAUI property to the native NavigationView.CompactPaneLength property. The fix enables both initial and dynamic configuration of the collapsed pane width when using CollapseStyle.Partial.

Changes:

• Added property change callback to trigger handler updates when CollapsedPaneWidth changes
• Registered mapper for CollapsedPaneWidth property in FlyoutPage handler
• Implemented mapper to apply CollapsedPaneWidth to native NavigationView.CompactPaneLength
• Added UI test to verify CollapsedPaneWidth works both initially and when changed dynamically

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/Controls/src/Core/PlatformConfiguration/WindowsSpecific/FlyoutPage.cs	Added property changed callback (OnCollapsedPaneWidthChanged) to trigger handler updates when CollapsedPaneWidth property changes
src/Controls/src/Core/FlyoutPage/FlyoutPage.Mapper.cs	Registered mapper for CollapsedPaneWidthProperty and implemented MapCollapsedPaneWidth to apply the value to NavigationView.CompactPaneLength
src/Controls/tests/TestCases.HostApp/Issues/Issue33785.cs	Created UI test page that demonstrates CollapsedPaneWidth functionality with initial value (50) and dynamic change (100)
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33785.cs	Implemented automated UI test that verifies CollapsedPaneWidth changes are applied correctly using screenshot verification

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 33786

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 33786"

[kubaflo]

/azp run maui-pr-uitests

[kubaflo]

Could you please add the Windows snapshot? :)

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[kubaflo]

Could you please add a snapshot?

[devanathan-vaithiyanathan]

Could you please add a snapshot?

@kubaflo , CollapseStyle issue was resolved in PR #29927. We also need those changes for collapsedPaneWidth to work properly. I will add an image once PR #29927 is merged.

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[kubaflo]

Could you please check the ai's suggestions?

[kubaflo]

/review -b feature/enhanced-reviewer -p windows

[devanathan-vaithiyanathan]

@kubaflo , Based on AI suggestion, I have added the windows snapshot.

[kubaflo]

/review -b feature/enhanced-reviewer -p windows

[MauiBot]

AI Review Summary

@devanathan-vaithiyanathan — new AI review results are available based on this last commit: 24007f5. To request a fresh review after new comments or commits, comment /review rerun.

Review Sessions — click to expand

Gate — Test Before & After Fix

Gate Result: ✅ PASSED

Platform: WINDOWS · Base: main · Merge base: bb4e7040

Test	Without Fix (expect FAIL)	With Fix (expect PASS)
🖥️ Issue33785 Issue33785	✅ FAIL — 587s	✅ PASS — 532s

🔴 Without fix — 🖥️ Issue33785: FAIL ✅ · 587s

  Determining projects to restore...
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Build succeeded.
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Time Elapsed 00:06:13.57
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Test run for D:\a\1\s\artifacts\bin\Controls.TestCases.WinUI.Tests\Debug\net10.0\Controls.TestCases.WinUI.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in D:\a\1\s\artifacts\bin\Controls.TestCases.WinUI.Tests\Debug\net10.0\Controls.TestCases.WinUI.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 6/15/2026 11:47:09 AM FixtureSetup for Issue33785(Windows)
>>>>> 6/15/2026 11:47:17 AM VerifyFlyoutPageCollapsedPaneWidth Start
>>>>> 6/15/2026 11:47:22 AM VerifyFlyoutPageCollapsedPaneWidth Stop
>>>>> 6/15/2026 11:47:22 AM Log types: 
  Failed VerifyFlyoutPageCollapsedPaneWidth [5 s]
  Error Message:
   VisualTestUtils.VisualTestFailedException : 
Snapshot different than baseline: VerifyFlyoutPageCollapsedPaneWidth.png (13.16% difference)
If the correct baseline has changed (this isn't a a bug), then update the baseline image.
See test attachment or download the build artifacts to get the new snapshot file.

More info: https://aka.ms/visual-test-workflow

  Stack Trace:
     at VisualTestUtils.VisualRegressionTester.Fail(String message) in /_/src/TestUtils/src/VisualTestUtils/VisualRegressionTester.cs:line 162
   at VisualTestUtils.VisualRegressionTester.VerifyMatchesSnapshot(String name, ImageSnapshot actualImage, String environmentName, ITestContext testContext) in /_/src/TestUtils/src/VisualTestUtils/VisualRegressionTester.cs:line 123
   at Microsoft.Maui.TestCases.Tests.UITest.<VerifyScreenshot>g__Verify|13_0(String name, <>c__DisplayClass13_0&) in /_/src/Controls/tests/TestCases.Shared.Tests/UITest.cs:line 477
   at Microsoft.Maui.TestCases.Tests.UITest.VerifyScreenshot(String name, Nullable`1 retryDelay, Nullable`1 retryTimeout, Int32 cropLeft, Int32 cropRight, Int32 cropTop, Int32 cropBottom, Double tolerance, Boolean includeTitleBar) in /_/src/Controls/tests/TestCases.Shared.Tests/UITest.cs:line 309
   at Microsoft.Maui.TestCases.Tests.Issues.Issue33785.VerifyFlyoutPageCollapsedPaneWidth() in /_/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33785.cs:line 20
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

NUnit Adapter 4.5.0.0: Test execution complete
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.11]   Discovering: Controls.TestCases.WinUI.Tests
[xUnit.net 00:00:00.33]   Discovered:  Controls.TestCases.WinUI.Tests
Results File: D:\a\1\s\CustomAgentLogsTmp\UITests\TestResults\Issue33785.trx

Total tests: 1
     Failed: 1
Test Run Failed.
 Total time: 35.1453 Seconds
>>> TRX_RESULT_FILE: D:\a\1\s\CustomAgentLogsTmp\UITests\TestResults\Issue33785.trx

🟢 With fix — 🖥️ Issue33785: PASS ✅ · 532s

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  Controls.Maps -> D:\a\1\s\artifacts\bin\Controls.Maps\Debug\net10.0-windows10.0.19041.0\Microsoft.Maui.Controls.Maps.dll
  Controls.Foldable -> D:\a\1\s\artifacts\bin\Controls.Foldable\Debug\net10.0-windows10.0.19041.0\Microsoft.Maui.Controls.Foldable.dll
  Microsoft.AspNetCore.Components.WebView.Maui -> D:\a\1\s\artifacts\bin\Microsoft.AspNetCore.Components.WebView.Maui\Debug\net10.0-windows10.0.19041.0\Microsoft.AspNetCore.Components.WebView.Maui.dll
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Build succeeded.
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Time Elapsed 00:06:38.49
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  Controls.TestCases.WinUI.Tests -> D:\a\1\s\artifacts\bin\Controls.TestCases.WinUI.Tests\Debug\net10.0\Controls.TestCases.WinUI.Tests.dll
Test run for D:\a\1\s\artifacts\bin\Controls.TestCases.WinUI.Tests\Debug\net10.0\Controls.TestCases.WinUI.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in D:\a\1\s\artifacts\bin\Controls.TestCases.WinUI.Tests\Debug\net10.0\Controls.TestCases.WinUI.Tests.dll
   NUnit3TestExecutor discovered 1 of 1 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 6/15/2026 11:56:04 AM FixtureSetup for Issue33785(Windows)
>>>>> 6/15/2026 11:56:12 AM VerifyFlyoutPageCollapsedPaneWidth Start
>>>>> 6/15/2026 11:56:15 AM VerifyFlyoutPageCollapsedPaneWidth Stop
  Passed VerifyFlyoutPageCollapsedPaneWidth [3 s]
NUnit Adapter 4.5.0.0: Test execution complete
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.13]   Discovering: Controls.TestCases.WinUI.Tests
[xUnit.net 00:00:00.34]   Discovered:  Controls.TestCases.WinUI.Tests
Results File: D:\a\1\s\CustomAgentLogsTmp\UITests\TestResults\Issue33785.trx

Test Run Successful.
Total tests: 1
     Passed: 1
 Total time: 26.1996 Seconds
>>> TRX_RESULT_FILE: D:\a\1\s\CustomAgentLogsTmp\UITests\TestResults\Issue33785.trx

📁 Fix files reverted (3 files)

• eng/pipelines/ci-copilot.yml
• src/Controls/src/Core/FlyoutPage/FlyoutPage.Mapper.cs
• src/Controls/src/Core/PlatformConfiguration/WindowsSpecific/FlyoutPage.cs

---

UI Tests — FlyoutPage

Detected UI test categories: FlyoutPage

❌ Deep UI tests — 46 passed, 1 failed across 1 category on platform-pool agent (replaces in-process counts above).

🧪 UI Test Execution Results (deep, platform pool)

Category	Tests	Snapshot diffs
FlyoutPage	46/47 (1 ❌)	—

❌ FlyoutPage — 1 failed test

Bugzilla32902Test

System.TimeoutException : Timed out waiting for element...
at UITest.Appium.HelperExtensions.Wait(Func`1 query, Func`2 satisfactory, String timeoutMessage, Nullable`1 timeout, Nullable`1 retryFrequency) in /_/src/TestUtils/src/UITest.Appium/HelperExtensions.cs:line 2757
   at UITest.Appium.HelperExtensions.WaitForAtLeastOne(Func`1 query, String timeoutMessage, Nullable`1 timeout, Nullable`1 retryFrequency) in /_/src/TestUtils/src/UITest.Appium/HelperExtensions.cs:line 2784
   at UITest.Appium.HelperExtensions.WaitForElement(IApp app, String marked, String timeoutMessage, Nullable`1 timeout, Nullable`1 retryFrequency, Nullable`1 postTimeout) in /_/src/TestUtils/src/UITest.Appium/HelperExtensions.cs:line 793
   at Microsoft.Maui.TestCases.Tests.Issues.Bugzilla32902.Bugzilla32902Test() in /_/src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Bugzilla/Bugzilla32902.cs:line 18
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.
...

📎 Download drop-deep-uitests artifact (TRX + snapshot diffs)

---

Pre-Flight — Context & Validation

Issue: #33785 - [Windows] FlyoutPage CollapsedPaneWidth Not Working
PR: #33786 - Windows FlyoutPage CollapsedPaneWidth fix
Platforms Affected: windows
Files Changed: 12 implementation/infrastructure, 4 test/snapshot

Key Findings

• GitHub PR metadata and comments could not be fetched because gh is unauthenticated; local branch pr-review-33786 is the squashed PR and origin/main...HEAD was used for context.
• Product fix files are src/Controls/src/Core/FlyoutPage/FlyoutPage.Mapper.cs and src/Controls/src/Core/PlatformConfiguration/WindowsSpecific/FlyoutPage.cs.
• Regression coverage is a Windows FlyoutPage UI test: VerifyFlyoutPageCollapsedPaneWidth.
• Supplied gate result: Gate PASSED — tests fail without fix and pass with the PR fix. Gate was not re-run and gate/content.md was not touched.

Code Review Summary

Verdict: NEEDS_CHANGES
Confidence: low
Errors: 1 | Warnings: 0 | Suggestions: 0

Key code review findings:

• ❌ .github/scripts/Review-PR.ps1 token telemetry parser accepts an optional compact-number suffix but calls .ToUpperInvariant() on the suffix without a null guard.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #33786	Register a dedicated CollapsedPaneWidthProperty mapper and call Handler.UpdateValue(nameof(CollapsedPaneWidthProperty)) from the attached-property changed callback.	✅ PASSED (Gate)	FlyoutPage.Mapper.cs, WindowsSpecific/FlyoutPage.cs	Original PR

---

Code Review — Deep Analysis

Code Review — PR #33786

Independent Assessment

What this changes: Windows FlyoutPage.CollapsedPaneWidth is mapped to RootNavigationView.CompactPaneLength and refreshed on property changes; the local squashed PR branch also contains Copilot review pipeline/token-usage changes.
Inferred motivation: Fix Windows FlyoutPage.CollapsedPaneWidth not applying initially or after runtime changes, and improve PR-review telemetry.

Reconciliation with PR Narrative

Author claims: GitHub PR metadata could not be fetched because gh is unauthenticated in this environment. The local diff and gate result identify the gate-verified product issue as [Windows] FlyoutPage CollapsedPaneWidth Not Working.
Agreement/disagreement: The local product-code changes match that issue. The broader local diff also contains CI pipeline script changes.

Prior Review Reconciliation

Prior ❌ Error Finding	Source	Status	Evidence
No prior review data available	GitHub API unavailable	N/A	gh reported authentication required.

Blast Radius Assessment

• Runs for all instances: Windows FlyoutPage mapper path; only native RootNavigationView compact pane length is updated.
• Startup impact: no app startup impact beyond normal handler mapper initialization.
• Static/shared state: no product static/shared state introduced.

CI Status

• Required-check result: undetermined; gh pr checks unavailable due missing authentication.
• Classification: undetermined.
• Action taken: confidence capped low for CI visibility; gate result supplied by caller is trusted for the product regression.

Findings

❌ Error — Accepted context footer format can crash Copilot telemetry parsing

.github/scripts/Review-PR.ps1 accepts compact context lines without a suffix, but the conversion logic calls .ToUpperInvariant() on the optional suffix. This is outside the FlyoutPage gate target but is in the local PR diff and should be addressed before merge.

⚠️ Warning — None

💡 Suggestion — None

Failure-Mode Probing

• Property set before handler exists: the PR mapper reads the attached property after handler creation.
• Runtime property change: the PR property callback calls Handler.UpdateValue(...) to re-run the mapper.
• Null/disconnected handler: the property callback and mapper guard null handler/platform-view states.
• Non-Windows platforms: changes are compiled under Windows-specific code paths or platform-specific APIs.

Verdict: NEEDS_CHANGES

Confidence: low
Summary: The Windows FlyoutPage fix appears sound for the gate scenario, but required CI could not be queried and a separate CI telemetry parsing issue exists in the local diff.

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Fix — Analysis & Comparison

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix-1	Reuse CollapseStyleProperty mapper; set CompactPaneLength during partial-collapse mapping and update CollapseStyleProperty when CollapsedPaneWidth changes.	✅ PASS	2 files	Smallest alternative, but width changes are routed through an indirectly related mapper key.
2	try-fix-2	Add Windows-guarded ApplyCollapsedPaneWidth helper and call it from initial collapse-style mapping plus runtime property changes.	✅ PASS	2 files	Functional, but expert self-review found a moderate layering concern.
PR	PR #33786	Register a dedicated CollapsedPaneWidthProperty mapper and call Handler.UpdateValue(nameof(CollapsedPaneWidthProperty)) from the property callback.	✅ PASSED (Gate)	2 files	Most explicit and best aligned with handler mapper/property patterns.

Cross-Pollination

Model/Reviewer	Round	New Ideas?	Details
code-review + maui-expert-reviewer guidance	1	Yes	Candidate 1: collapse-style-dependent compact width.
code-review + maui-expert-reviewer guidance	2	Yes	Candidate 2: direct Windows helper for native apply.
code-review + maui-expert-reviewer guidance	3	No	Remaining options were trivial variations: remapping FlyoutLayoutBehavior instead of CollapseStyle, or duplicating PR's dedicated mapper with cosmetic changes.

Exhausted: Yes
Selected Fix: PR #33786 — It passes the supplied gate and is preferable to both passing alternatives because it keeps CollapsedPaneWidth as an explicit mapper-owned property update. Candidate 1 is more indirect; Candidate 2 crosses the configuration/handler abstraction boundary.

Candidate Details

• try-fix-1/content.md contains approach, diff, test result, and analysis.
• try-fix-2/content.md contains approach, diff, test result, and analysis.
• Full test logs and self-review artifacts are under try-fix/try-fix-1/ and try-fix/try-fix-2/.

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Report — Final Recommendation

Comparative Report — PR #33786

Candidates compared

Rank	Candidate	Regression result	Assessment
1	pr-plus-reviewer	✅ Passes supplied gate	Best candidate. Keeps the PR's explicit mapper-based CollapsedPaneWidthProperty fix and adds the expert reviewer's null-safe compact-number parser correction in .github/scripts/Review-PR.ps1.
2	pr	✅ Passes supplied gate	The Windows FlyoutPage fix is the best product-code approach: a dedicated mapper key plus property-changed UpdateValue is clear and consistent with handler mapper patterns. Ranked below pr-plus-reviewer only because it leaves the expert reviewer's major parser issue unresolved.
3	try-fix-1	✅ Pass	Functionally fixes the FlyoutPage bug by setting CompactPaneLength from MapCollapseStyle and remapping CollapseStyleProperty when width changes. It is smaller, but less direct because a width change is routed through an indirectly related mapper key.
4	try-fix-2	✅ Pass	Functionally fixes the FlyoutPage bug, but crosses abstraction layers by adding a Windows-native apply helper to the platform-configuration API type. This is less aligned with MAUI handler mapper conventions than the PR.

No candidate from STEP 5a failed regression tests, so the ranking is based on correctness, maintainability, and reviewer findings. If any candidate had failed regression tests, it would be ranked below all passing candidates.

Why pr-plus-reviewer wins

The core PR fix is the most maintainable FlyoutPage solution because CollapsedPaneWidth becomes an explicit mapper-owned value rather than a side effect of collapse-style mapping or a direct platform-configuration native mutation. The expert reviewer found a separate major issue in the PR's Copilot telemetry parser: the compact-number suffix is optional, but .ToUpperInvariant() is called on $Matches['suffix'] without a null-safe cast. Applying that feedback produces pr-plus-reviewer, which retains the passing product fix and removes a review-step failure mode.

Winning candidate

pr-plus-reviewer

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Future Action — review latest findings

No alternative fix was selected for this run. Review the session findings and CI results before merging.