Fixed Shell TitleView disappears when switching between tabs on Android #33469

KarthikRajaKalaimani · 2026-01-12T06:07:59Z

Issue Details:

Shell TitleView disappears when switching between tabs on Android (regression from MAUI 9.0.30).

Root Cause:

When switching tabs, we reuses fragments by hiding/showing them if the ShellNavigationSource is ShellSectionChanged in ShellItemRendererBase class(line number 235 to 242). When a fragment becomes visible again, the TitleView handler update isn't automatically triggered, leaving the TitleView invisible.

Description of Change:

Updated TitleView of the shellToobar when fragment becomes visible after being hidden, ensuring TitleView appears when switching back to a tab.

Tested the behavior in the following platforms.

Android
Windows
iOS
Mac

Reference:

N/A

Issues Fixed:

Fixes #33304

Screenshots

Before	After
Screen.Recording.2026-01-12.at.11.31.08.AM.mov	Screen.Recording.2026-01-12.at.11.34.16.AM.mov

dotnet-policy-service · 2026-01-12T06:08:20Z

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

Copilot

Pull request overview

This PR fixes a regression in .NET MAUI 9.0.30 where Shell TitleView disappears when switching between tabs on Android. The fix ensures that when a fragment becomes visible after being hidden (during tab switching), the TitleView is properly refreshed.

Changes:

Added OnHiddenChanged override in ShellSectionRenderer to update TitleView when fragment becomes visible
Stored Toolbar reference as field to enable TitleView updates during fragment visibility changes
Added UI test to verify TitleView persists when switching tabs

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
`ShellSectionRenderer.cs`	Stores `Toolbar` reference as `_shellToolbar` field and overrides `OnHiddenChanged` to update TitleView when fragment becomes visible after tab switch
`PublicAPI.Unshipped.txt`	Documents the new public API method `OnHiddenChanged` override for Android
`Issue33304.cs` (HostApp)	Implements test page with Shell containing multiple tabs and a TitleView to reproduce the issue
`Issue33304.cs` (Tests)	Adds automated UI test that switches tabs and verifies TitleView persists

Copilot · 2026-01-16T14:15:30Z

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellSectionRenderer.cs

+		{
+			base.OnHiddenChanged(hidden);
+
+			if (!hidden)


Potential null reference exception if _shellToolbar or _shellToolbar.Handler is null. The OnHiddenChanged method can be called before OnCreateView (where _shellToolbar is initialized) or after disposal (where it's not explicitly set to null). Add null checks: if (!hidden && _shellToolbar?.Handler != null).

Suggested change

if (!hidden)

if (!hidden && _shellToolbar?.Handler != null)

Copilot · 2026-01-16T14:15:30Z

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellSectionRenderer.cs

+
+			if (!hidden)
+			{
+				_shellToolbar.Handler.UpdateValue("TitleView");


Using a magic string "TitleView" instead of nameof(Toolbar.TitleView) makes the code fragile to refactoring. Use nameof(Toolbar.TitleView) for type safety and consistency with the rest of the codebase (see line 630 in ShellToolbarTracker.cs which uses nameof(Toolbar.TitleView)).

Copilot · 2026-01-16T14:15:30Z

src/Controls/tests/TestCases.HostApp/Issues/Issue33304.cs

+				Text = "TitleView",
+				AutomationId = "HomeTitleView"
+			});
+			// Shell.SetFlyoutBehavior(FlyoutBehavior.Disabled);


Remove commented-out code. If this line was used during development/testing, it should either be removed or uncommented with a comment explaining why it's needed for the test.

Suggested change

// Shell.SetFlyoutBehavior(FlyoutBehavior.Disabled);

kubaflo · 2026-01-25T15:44:11Z

🤖 AI Summary

📊 Expand Full Review

🔍 Pre-Flight — Context & Validation

📝 Review Session — Added null check for handler · 7cb9cee

Bug: On Android, a Shell.TitleView displays correctly on the first tab. When switching to the second tab, the TitleView disappears, even though it is defined in the Shell. Switching to a third tab causes the TitleView to render correctly again.

Steps to Reproduce:

Create a new .NET MAUI app with Shell
Define a Shell.TitleView in the Shell (e.g., a custom layout or label)
Configure a TabBar with at least three tab items
Build and run targeting Android
Navigate between tabs - TitleView appears on first tab, disappears on second tab, reappears on third

Platforms Affected:

Android
iOS
Windows
MacCatalyst

Regression: Yes - regressed in MAUI 9.0.30

Root Cause (from PR): When switching tabs, fragments are reused by hiding/showing them (in ShellItemRendererBase, lines 235-242). When a fragment becomes visible again via OnHiddenChanged, the TitleView handler update isn't automatically triggered, leaving the TitleView invisible.

🧪 Tests — Verification

📝 Review Session — Added null check for handler · 7cb9cee

Status: ✅ COMPLETE

PR includes UI tests
Tests reproduce the issue (verified to FAIL without fix)
Tests follow naming convention (Issue33304)

Test Files:

HostApp: src/Controls/tests/TestCases.HostApp/Issues/Issue33304.cs
NUnit: src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33304.cs

Test Logic:

Wait for HomeTabLabel
Tap Search tab
Wait for SearchTabLabel
Tap Home tab
Wait for HomeTabLabel
Verify HomeTitleView is visible (this fails without fix)

🚦 Gate — Test Verification

📝 Review Session — Added null check for handler · 7cb9cee

Status: ✅ PASSED

Tests FAIL without fix (bug reproduced)
Tests PASS with fix

Result: PASSED ✅

Verification Details:

With fix: Issue33304Test passes in 6 seconds - HomeTitleView found immediately after switching back to Home tab
Without fix: Issue33304Test fails - Appium repeatedly polls for HomeTitleView (26+ attempts over 15 seconds) and times out because TitleView disappears
Platform tested: Android (emulator-5556)

🔧 Fix — Analysis & Comparison

📝 Review Session — Added null check for handler · 7cb9cee

Status: ✅ COMPLETE

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix	Post delayed `UpdateTitleView()` in `ShellToolbarTracker.OnShellNavigated()` when `ShellSectionChanged`	❌ FAIL	`ShellToolbarTracker.cs` (+12)	Navigation event fires before fragment visibility change completes
PR	PR #33469	Override `OnHiddenChanged` to update TitleView handler when fragment becomes visible	✅ PASS (Gate)	`ShellSectionRenderer.cs` (+16), `PublicAPI.Unshipped.txt` (+1)	Original PR - uses fragment lifecycle

Try-Fix Attempt #1 Analysis:

Approach: Modified ShellToolbarTracker.OnShellNavigated() to post a delayed UpdateTitleView() call when navigation source is ShellSectionChanged
Why it failed: OnShellNavigated fires before fragment visibility change completes. Even posting via _platformToolbar.Post() doesn't work because:
1. Navigation events fire at navigation start, not at fragment visibility change
2. A single Post() delays by only one message queue cycle - insufficient for fragment transition
3. No direct access to fragment lifecycle from ShellToolbarTracker

Exhausted: Yes - Alternative approaches from navigation event system cannot reliably fix this issue because they don't have visibility into fragment lifecycle timing. The PR's OnHiddenChanged approach is the correct solution.

Selected Fix: PR's fix - OnHiddenChanged override is the optimal location because:

It fires at the exact moment when fragment visibility changes (the root cause trigger)
ShellSectionRenderer has direct access to _shellToolbar field
Minimal code footprint (11 lines of actual logic)
No refactoring of class hierarchy required
Proper null checks (_shellToolbar?.Handler != null) prevent edge case crashes

📋 Report — Final Recommendation

📝 Review Session — Added null check for handler · 7cb9cee

Status: ✅ COMPLETE

Final Recommendation: APPROVE

Root Cause Analysis

When switching tabs in Shell on Android, fragments are reused via HideEx()/ShowEx() calls in ShellItemRendererBase (lines 235-242). When a fragment becomes visible again through OnHiddenChanged, the TitleView handler's update isn't automatically triggered, leaving the TitleView invisible.

Key Findings

Bug confirmed as regression - Worked in 9.0.120, broken in 9.0.30+
Android-only issue - Fragment lifecycle specific to Android
Fix location is optimal - OnHiddenChanged in ShellSectionRenderer is the exact lifecycle hook needed
Code quality is good - Proper null checks, uses nameof(), minimal footprint

Verdict

✅ APPROVE - This is a well-crafted fix that correctly addresses the regression. The approach is minimal, targeted, and uses proper Android lifecycle patterns.

Minor Issues

Commented-out code in test file (Issue33304.cs line 13) should be removed before merge

_{🤖 Generated by Copilot CLI}

PureWeen · 2026-01-29T20:57:06Z

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellSectionRenderer.cs

 		protected IShellContext ShellContext => _shellContext;
 		IShellSectionController SectionController => (IShellSectionController)ShellSection;
 		IMauiContext MauiContext => ShellContext.Shell.Handler.MauiContext;
+		Toolbar _shellToolbar;


Can you set this to null inside Destroy?

Can you set this to null inside Destroy?

I set _shellToolbar to null on Destroy method.

PureWeen · 2026-01-31T13:57:43Z

/rebase

dotnet-policy-service bot added the community ✨ Community Contribution label Jan 12, 2026

dotnet-policy-service bot added the partner/syncfusion Issues / PR's with Syncfusion collaboration label Jan 12, 2026

Tamilarasan-Paranthaman added platform/android area-controls-shell Shell Navigation, Routes, Tabs, Flyout labels Jan 12, 2026

sheiksyedm marked this pull request as ready for review January 16, 2026 14:05

Copilot AI review requested due to automatic review settings January 16, 2026 14:05

Copilot started reviewing on behalf of sheiksyedm January 16, 2026 14:06 View session

Copilot AI reviewed Jan 16, 2026

View reviewed changes

kubaflo previously approved these changes Jan 25, 2026

View reviewed changes

PureWeen requested changes Jan 29, 2026

View reviewed changes

KarthikRajaKalaimani dismissed kubaflo’s stale review via 2f1b346 January 30, 2026 09:51

KarthikRajaKalaimani added 9 commits January 31, 2026 13:58

Fixed [Android] TitleView defined in Shell is lost when changing tabs

8d638fb

Test case added

1c28450

Modified the fix

202ee09

Removed unwanted changes

e817775

Removed comments

8aa801b

Renamed the field

2960829

renamed the private field

c74f8aa

Added null check for handler

493408e

Set _shellToolbar to null on Destroy method

9eeed4d

github-actions bot force-pushed the fix-33304 branch from 2f1b346 to 9eeed4d Compare January 31, 2026 13:58

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Fixed Shell TitleView disappears when switching between tabs on Android #33469

Fixed Shell TitleView disappears when switching between tabs on Android #33469

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Final Recommendation: APPROVE

Root Cause Analysis

Key Findings

Verdict

Minor Issues

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Fixed Shell TitleView disappears when switching between tabs on Android #33469

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KarthikRajaKalaimani commented Jan 12, 2026

Issue Details:

Root Cause:

Description of Change:

Reference:

Issues Fixed:

Screenshots

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Final Recommendation: APPROVE

Root Cause Analysis

Key Findings

Verdict

Minor Issues

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