[Windows] - Fix Grid layout not updating when Row/Column changed dynamically

[prakashKannanSf3972]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Root Cause

• When Grid.Row or Grid.Column properties are updated on a Grid element nested within another Grid, the current implementation only invalidates the element itself and does not propagate the invalidation to its parent. As a result, the parent layout is not re-measured or arranged correctly, leading to inaccurate or incomplete rendering.

Description of Change

• Improved parent layout invalidation for Grid on Windows to ensure UI updates correctly when Grid.Row or Grid.Column properties change.

Issues Fixed

Fixes #20404

Tested the behaviour in the following platforms

• Android
• Windows
• iOS
• Mac

Output

Before	After
BeforeFix_Grid.mp4	AfterFix_Grid.mp4

[dotnet-policy-service]

Hey there @@prakashKannanSf3972! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jsuarezruiz]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jsuarezruiz]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull Request Overview

This PR ensures that dynamic changes to Grid.Row and Grid.Column on Windows correctly invalidate the parent layout so the UI updates without requiring a window resize.

• Added a UI sample page in the HostApp for toggling row/column at runtime.
• Added a cross-platform UI test in TestCases.Shared.Tests to verify dynamic grid updates.
• Updated Grid.cs to propagate measure invalidation to the parent grid on Windows.

Reviewed Changes

Copilot reviewed 3 out of 11 changed files in this pull request and generated 2 comments.

File	Description
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue20404.cs	New UITest verifying dynamic row/column toggles trigger layout updates.
src/Controls/tests/TestCases.HostApp/Issues/Issue20404.cs	New sample page with buttons to toggle grid row/column dynamically.
src/Controls/src/Core/Layout/Grid.cs	Updated Invalidate method to explicitly invalidate parent grid on Windows.

[kubaflo]

/azp run maui-pr-uitests

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[kubaflo]

Could you please review the AI's summary?

[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 -- 30206

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 30206"

[Dhivya-SF4094]

Could you please review the AI's summary?

Validated the AI summary and addressed the concerns accordingly.
Note: The issue linked to this PR has been closed as not planned

[sheiksyedm]

/azp run maui-pr-uitests , maui-pr-devicetests

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[MauiBot]

🚦 Gate — Test Verification

📊 Expand Full Gate — 5e4a947 · Addressed AI summary

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Gate Result: ❌ FAILED

Platform: WINDOWS

Tests Detected

#	Type	Test Name	Filter
1	UITest	Issue20404	Issue20404

Verification

Step	Expected	Actual	Result
Without fix	FAIL	FAIL	✅
With fix	PASS	FAIL	❌

Details

• ❌ Failed: DynamicGridRowColumnChangeShouldInvalidate [3 s]
• 📋 Error: VisualTestUtils.VisualTestFailedException :
  Snapshot different than baseline: AfterGridRowToggled.png (36.09% difference)
  If the correct baseline has changed (this isn't a a bug), then update the b...
• ❌ Failed: DynamicGridRowColumnChangeShouldInvalidate [2 s]
• 📋 Error: VisualTestUtils.VisualTestFailedException :
  Snapshot different than baseline: AfterGridRowToggled.png (6.51% difference)
  If the correct baseline has changed (this isn't a a bug), then update the ba...

Fix Files Reverted

• eng/pipelines/ci-copilot.yml
• src/Controls/src/Core/Layout/Grid.cs

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Base Branch: main | Merge Base: 720a9d4

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[MauiBot]

🤖 AI Summary

📊 Expand Full Review — 5e4a947 · Addressed AI summary

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🔍 Pre-Flight — Context & Validation

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Issue: #20404 - Changing Grid.Row does not update layout until window is resized
PR: #30206 - [Windows] Fix Grid layout not updating when Row/Column changed dynamically
Platforms Affected: Windows (WinUI) — issue is Windows-specific per labels; root cause (logic asymmetry) is cross-platform
Files Changed: 1 implementation (Grid.cs), 1 test page (Issue20404.cs), 1 test class (Issue20404.cs), 8 snapshot PNGs

Key Findings

• Root cause: Grid.Invalidate() has an else if asymmetry. When bindable is Grid, it calls grid.InvalidateMeasure() on the child but never propagates to the parent. The else if for non-Grid elements correctly calls parentGrid.InvalidateMeasure() — but this branch is never reached when the child IS a Grid (since Grid is also Element, the else if is mutually exclusive).
• PR's fix: Adds #if WINDOWS block inside the if (bindable is Grid) branch, calling containerGrid.InvalidateMeasure() + return if parent is Grid. Also includes a return statement that is logically harmless but confusing.
• Issues with PR's fix:
  1. #if WINDOWS compile-time guard for a logical inconsistency present on all platforms
  2. The return exits the method early (harmless now, but fragile)
  3. Only handles Grid-in-Grid; a Grid nested in StackLayout is still affected
  4. Snapshot PNG baselines captured locally → don't match CI rendering
• Gate FAILED: DynamicGridRowColumnChangeShouldInvalidate fails — screenshot comparison fails with 36.09% / 6.51% difference on snapshots that don't match CI.
• Prior agent review found: Full 4-phase review already performed (see MauiBot comment). Candidate Update README.md #5 (change else if → if) found to be the cleanest fix; Candidate Update README.md #2 (same Grid.cs fix + GetRect() assertions) also passed.
• Inline review comment: Copilot reviewer suggested OperatingSystem.IsWindows() runtime check instead of #if WINDOWS (marked resolved but concern not fully addressed).
• Issue closed as "not planned" — PR is fixing a bug on the issue closed before it was opened.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #30206	#if WINDOWS block: containerGrid.InvalidateMeasure() + return when child is Grid with Grid parent	❌ FAILED (Gate)	Grid.cs, 8 snapshot PNGs	Snapshot mismatch in CI; fix too narrow; #if WINDOWS unnecessary

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🔧 Fix — Analysis & Comparison

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Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix (claude-opus-4.6)	Remove else from else if in Grid.Invalidate() standalone if; GetRect() test assertions	PASS	Grid.cs, Issue20404.cs	Most minimal 1-char change; cross-platform; no #if WINDOWS
2	try-fix (claude-sonnet-4.6)	Add if (grid.Parent is Grid parentGrid) { parentGrid.InvalidateMeasure(); } inside if (bindable is Grid) block; kept else if; GetRect() assertions	PASS	Grid.cs, Issue20404.cs	Cross-platform; preserves existing structure; adds minimal parent check
3	try-fix (gpt-5.3-codex)	Walk full ancestor chain invalidating ALL ancestor Grids; GetRect() assertions	PASS	Grid.cs, Issue20404.cs	More thorough but overkill; handles deeply nested Grids
4	try-fix (gpt-5.1-codex)	Invalidate nearest Layout parent (not just Grid parent); covers non-Grid parents too; GetRect() assertions	PASS	Grid.cs, Issue20404.cs	Broader fix; handles Grid-in-StackLayout-in-Grid case
5	try-fix (claude-sonnet-4.6)	Override OnChildAdded/OnChildRemoved to subscribe to PropertyChanged; call InvalidateMeasure() on parent Grid	PASS	Grid.cs, Issue20404.cs, 2xPublicAPI.Unshipped.txt	Different paradigm (parent observes children); adds public API surface; most complex
PR	PR #30206	#if WINDOWS block: containerGrid.InvalidateMeasure() + return when child is Grid with Grid parent	FAILED (Gate)	Grid.cs, 8 snapshot PNGs	Snapshot mismatch in CI; fix too narrow; #if WINDOWS unnecessary

Cross-Pollination

Model	Round	New Ideas?	Details
claude-opus-4.6	2	Yes	Fix in Windows LayoutHandler/LayoutPanel at platform boundary
claude-sonnet-4.6	2	Yes	Override OnChildPropertyChanged in Grid became Attempt 5
gpt-5.3-codex	2	Yes	Force Windows arrange invalidation via InvalidateArrange() on parent
gpt-5.1-codex	2	Yes	Platform-specific handler hook for Windows native panel invalidation
claude-opus-4.6	3	No	NO NEW IDEAS "Attempt 1 is the minimal, correct fix"
claude-sonnet-4.6	3	Yes	Override InvalidateMeasure() on Grid to chain to Parent
gpt-5.3-codex	3	Yes	Layout-version invalidation + InvalidateArrange() targeting stale arrange cache
gpt-5.1-codex	3	Yes	Hook into attached BindableProperty changed callback to walk up immediately

Exhausted: Yes (max 3 rounds reached)
Selected Fix: Candidate #1 (remove else from else if) Most minimal fix: 1-character change in Grid.cs. Directly fixes the logical root cause (decouples the two independent checks). Cross-platform, no #if WINDOWS, no added public API surface, no event subscriptions. Test: replace VerifyScreenshot with GetRect() position assertions.

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📋 Report — Final Recommendation

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⚠️ Final Recommendation: REQUEST CHANGES

Phase Status

Phase	Status	Notes
Pre-Flight	✅ COMPLETE	Issue #20404, Windows-only layout staleness bug when Grid.Row/Column set dynamically on child Grid
Gate	❌ FAILED	Windows — test fails even with PR's fix (snapshot PNG baseline mismatch: 36.09% / 6.51% diff)
Try-Fix	✅ COMPLETE	5 attempts, all 5 passing; better fix found (Candidate #1)
Report	✅ COMPLETE

Summary

PR #30206 fixes a real, reproducible bug: calling Grid.SetRow()/Grid.SetColumn() dynamically on a child Grid element leaves the parent Grid's layout stale on Windows (WinUI) until a window resize forces re-measurement. The PR's fix is on the right track but uses unnecessary #if WINDOWS compile-time guards, includes a confusing return statement, and ships snapshot PNG baselines captured on the author's machine that don't match the CI rendering environment — causing the gate to fail even with the fix applied.

Try-Fix exploration found 5 independent passing fixes. The simplest and best is Candidate #1: remove else from else if in Grid.Invalidate(), making both checks independent. This is a 1-character change that directly fixes the logical root cause, is cross-platform, and requires no #if WINDOWS guard. The test must also be updated to use GetRect() position assertions instead of VerifyScreenshot().

Root Cause

Grid.Invalidate() has a structural asymmetry using else if:

if (bindable is Grid grid)
{
    grid.InvalidateMeasure();   // only child is invalidated
}
else if (bindable is Element element && element.Parent is Grid parentGrid)
{
    parentGrid.InvalidateMeasure();  // never reached when child IS a Grid!
}

Since Grid is also an Element, the else if condition is mutually exclusive with the first if. When a child is a Grid, only that child gets InvalidateMeasure() — the parent Grid never does. On Android/iOS, the native layout system propagates invalidation upward automatically, masking this bug. On Windows/WinUI it doesn't, so the parent Grid never re-measures.

Fix Quality

PR's fix — ❌ FAILED gate:

• #if WINDOWS compile-time guard for a cross-platform logical inconsistency — unnecessary
• return exits the Invalidate method early (harmless today, fragile for future changes)
• Only handles the Grid-in-Grid case; a Grid nested in other layout types is unaffected
• Snapshot PNG baselines were captured on author's machine; don't match CI environment

Recommended fix — Candidate #1 (✅ PASS):

src/Controls/src/Core/Layout/Grid.cs:

-        else if (bindable is Element element && element.Parent is Grid parentGrid)
+
+        if (bindable is Element element && element.Parent is Grid parentGrid)

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue20404.cs: Replace VerifyScreenshot() calls with GetRect() position assertions on DynamicLabel:

// After ToggleRow: DynamicGrid moves to row 0 → label Y should decrease
var rectBefore = App.WaitForElement("DynamicLabel").GetRect();
App.Tap("ToggleRowButton");
var rectAfter = App.WaitForElement("DynamicLabel").GetRect();
Assert.That(rectAfter.Y, Is.LessThan(rectBefore.Y));

Benefits:

• ✅ 1-character change in Grid.cs (else removed) — minimal, elegant
• ✅ Cross-platform — no #if WINDOWS, no OperatingSystem.IsWindows() check
• ✅ Fixes the logical root cause (decouples the two independent checks)
• ✅ Harmless on other platforms (extra InvalidateMeasure() on parent is a no-op when platform auto-propagates)
• ✅ Test uses GetRect() movement assertions — CI-environment-independent, no PNG baselines needed

Required Changes

1. src/Controls/src/Core/Layout/Grid.cs — Change else if to if (remove else)
2. src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue20404.cs — Replace VerifyScreenshot with GetRect() position assertions
3. Remove all snapshot PNG files (AfterGridRowToggled.png, AfterGridColumnToggled.png across Android/Mac/WinUI/iOS test projects) — unused when VerifyScreenshot is removed and incorrect anyway

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[kubaflo]

Test is failing; could you please verify?

[kubaflo]

Could you please check the AI's summary?