[Windows] Fix Issue29529VerifyPreviousPositionOnInsert test failure on candidate branch#35398
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…t failure on candidate branch (#35458) <!-- Please let the below note in for people that find this PR --> > [!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](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you! ### Root Cause PR #35398 protected grouped CollectionView from a mid-mutation `COMException` by short-circuiting `OnItemsVectorChanged` whenever WinUI raised `CollectionChange.Reset`. However, the Reset bail was applied unconditionally, preventing the corrective `ScrollIntoView(...)` logic used by `KeepItemsInView` / `KeepLastItemInView` from running for non-grouped controls as well. On Windows, `LoopableCollectionView` — the projection backing `CarouselView` — emits a full `CollectionChange.Reset` whenever the underlying `ObservableItemTemplateCollection` is rebuilt, including immediately after the initial `ItemsSource` assignment. Since the corrective scroll never executed after Reset, `CarouselView` and the connected `IndicatorView` remained on the wrong projected item, causing `VerifyAllIndicatorDotsShowShadowsWhenIndicatorSize` to fail because the expected indicator dots were not rendered for the visible item. ### Description of Change The fix replaces the unconditional Reset bail in `OnItemsVectorChanged` with three layered guards: 1. **Grouped + Reset → bail** Preserves the original `COMException` protection added in PR #35398 for grouped sources where the flattened projection can expose stale indices during rebuild. 2. **CarouselView + Reset + `Position != 0` → bail** Preserves the `Issue29529VerifyPreviousPositionOnInsert` fix from PR #35398. Without this guard, the deferred `ScrollIntoView(view[0])` call overrides the user-defined initial `Position` and reintroduces the cascading `PositionChanged` / `CurrentItemChanged` behavior. 3. **All other Reset cases → defer through `DispatcherQueue.TryEnqueue`** Restores the corrective `ScrollIntoViewIfNeeded()` behavior after WinUI finishes rebuilding `LoopableCollectionView`. The shared helper revalidates lifecycle state (`VirtualView`, `ListViewBase`, `CollectionViewSource?.View`, and `view?.Count`) before executing the scroll, ensuring the deferred path remains lifecycle-safe and null-safe. ### Issues Fixed Fixes `VerifyAllIndicatorDotsShowShadowsWhenIndicatorSize` test failure on candidate branch Tested the behaviour in the following platforms - [ ] Android - [x] Windows - [ ] iOS - [ ] Mac
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May 25, 2026
…n candidate branch (#35398) <!-- Please let the below note in for people that find this PR --> > [!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](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you! ### Root Cause On Windows, grouped CollectionView mutations rebuild WinUI’s internal flattened `ItemCollection` in stages while still raising `VectorChanged` synchronously mid-mutation. MAUI’s `OnItemsVectorChanged` handler calls `ScrollIntoView(...)` during this unstable state, re-entering WinUI while its projection is partially rebuilt, which triggers an uncatchable `STATUS_STOWED_EXCEPTION (0xc000027b)` surfaced as `COMException`. PR #24867 avoided the crash by unconditionally deferring `ScrollIntoView` through `DispatcherQueue.TryEnqueue`, but this introduced a regression in CarouselView (#29529 ), where the deferred callback overwrote the correct initial `Position` with stale values and triggered incorrect `PositionChanged` / `CurrentItemChanged` cascades. ### Description of Change The fix scopes the deferred `ScrollIntoView` path only to grouped CollectionView scenarios while preserving synchronous behavior for non-grouped controls like CarouselView. `OnItemsVectorChanged` now performs lifecycle and mode validation checks, skips unstable `CollectionChange.Reset` events, and uses `CollectionViewSource.IsSourceGrouped` as the discriminator. Grouped sources defer `ScrollIntoViewIfNeeded()` through `DispatcherQueue.TryEnqueue` to avoid WinUI mid-mutation crashes, while non-grouped sources continue using the synchronous path to preserve existing CarouselView behavior and avoid reintroducing #29529 . The shared `ScrollIntoViewIfNeeded()` helper revalidates lifecycle state, reads the latest projection from `CollectionViewSource.View`, and applies the appropriate scroll behavior for `KeepItemsInView` and `KeepLastItemInView` modes. ### Issues Fixed Fixes `Issue29529VerifyPreviousPositionOnInsert` test failure on candidate branch Tested the behaviour in the following platforms - [x] Android - [x] Windows - [x] iOS - [x] Mac
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May 25, 2026
…t failure on candidate branch (#35458) <!-- Please let the below note in for people that find this PR --> > [!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](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you! ### Root Cause PR #35398 protected grouped CollectionView from a mid-mutation `COMException` by short-circuiting `OnItemsVectorChanged` whenever WinUI raised `CollectionChange.Reset`. However, the Reset bail was applied unconditionally, preventing the corrective `ScrollIntoView(...)` logic used by `KeepItemsInView` / `KeepLastItemInView` from running for non-grouped controls as well. On Windows, `LoopableCollectionView` — the projection backing `CarouselView` — emits a full `CollectionChange.Reset` whenever the underlying `ObservableItemTemplateCollection` is rebuilt, including immediately after the initial `ItemsSource` assignment. Since the corrective scroll never executed after Reset, `CarouselView` and the connected `IndicatorView` remained on the wrong projected item, causing `VerifyAllIndicatorDotsShowShadowsWhenIndicatorSize` to fail because the expected indicator dots were not rendered for the visible item. ### Description of Change The fix replaces the unconditional Reset bail in `OnItemsVectorChanged` with three layered guards: 1. **Grouped + Reset → bail** Preserves the original `COMException` protection added in PR #35398 for grouped sources where the flattened projection can expose stale indices during rebuild. 2. **CarouselView + Reset + `Position != 0` → bail** Preserves the `Issue29529VerifyPreviousPositionOnInsert` fix from PR #35398. Without this guard, the deferred `ScrollIntoView(view[0])` call overrides the user-defined initial `Position` and reintroduces the cascading `PositionChanged` / `CurrentItemChanged` behavior. 3. **All other Reset cases → defer through `DispatcherQueue.TryEnqueue`** Restores the corrective `ScrollIntoViewIfNeeded()` behavior after WinUI finishes rebuilding `LoopableCollectionView`. The shared helper revalidates lifecycle state (`VirtualView`, `ListViewBase`, `CollectionViewSource?.View`, and `view?.Count`) before executing the scroll, ensuring the deferred path remains lifecycle-safe and null-safe. ### Issues Fixed Fixes `VerifyAllIndicatorDotsShowShadowsWhenIndicatorSize` test failure on candidate branch Tested the behaviour in the following platforms - [ ] Android - [x] Windows - [ ] iOS - [ ] Mac
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## What's Coming .NET MAUI inflight/candidate introduces significant improvements across all platforms with focus on quality, performance, and developer experience. This release includes 85 commits with various improvements, bug fixes, and enhancements. ## Button - [Android, iOS] Button: Fix VisualState properties not restored when leaving custom state by @BagavathiPerumal in #33346 <details> <summary>🔧 Fixes</summary> - [Button VisualStates do not work](#19690) </details> ## CollectionView - Fix CollectionView grid spacing updates for first row and column by @KarthikRajaKalaimani in #34527 <details> <summary>🔧 Fixes</summary> - [[MAUI] I2_Vertical grid for horizontal Item Spacing and Vertical Item Spacing - horizontally updating the spacing only applies to the second column](#34257) </details> - CarouselView: Fix cascading PositionChanged/CurrentItemChanged events on collection update by @praveenkumarkarunanithi in #31275 <details> <summary>🔧 Fixes</summary> - [[Windows] CurrentItemChangedEventArgs and PositionChangedEventArgs Not Working Properly in CarouselView](#29529) </details> - [Windows] Fixed ItemSpacing doesn't work in Carousel View by @SubhikshaSf4851 in #30014 <details> <summary>🔧 Fixes</summary> - [ItemSpacing on CarouselView is not applied on Windows.](#29772) </details> - Fix CollectionView not scrolling to top on iOS status bar tap by @jfversluis in #34687 <details> <summary>🔧 Fixes</summary> - [[iOS] UICollectionView ScrollToTop does not work](#19866) </details> - [iOS] Fixed CollectionView Scroll Jitter for TextType HTML Labels by @SubhikshaSf4851 in #34383 <details> <summary>🔧 Fixes</summary> - [CollectionView scrolling is jittery when ItemTemplate contains Label with TextType="Html" in .NET 10](#33065) </details> - Fix CollectionView Header is not visible when ItemsSource is not set and an EmptyView is set in iOS, Mac platform by @KarthikRajaKalaimani in #34989 <details> <summary>🔧 Fixes</summary> - [CollectionView Header is not visible when ItemsSource is not set and EmptyView is set in iOS, Mac platform](#34897) </details> - [Android] Fix CollectionView EmptyView not displayed correctly by @KarthikRajaKalaimani in #34956 <details> <summary>🔧 Fixes</summary> - [[Android] CollectionView - EmptyView not displayed correctly](#34861) </details> - [iOS] Fix CollectionView ScrollOffset not resetting when ItemsSource changes by @SyedAbdulAzeemSF4852 in #34488 <details> <summary>🔧 Fixes</summary> - [[IOS] CollectionView ScrollOffset does not reset when the ItemSource is changed in iOS.](#26366) - [Re-enable Issue7993 test on iOS/Catalyst - CollectionView scroll position not reset when updating ItemsSource](#33500) </details> - [Revert] [iOS] Fixed CollectionView Scroll Jitter for TextType HTML Labels by @SubhikshaSf4851 in #35341 ## Core Lifecycle - [Android] Fix NRE in ContainerView when Android Context is null during lifecycle transition by @rmarinho in #34901 <details> <summary>🔧 Fixes</summary> - [[Android] NullReferenceException in NavigationRootManager.Connect when mapping Window content](#34900) </details> ## DateTimePicker - [Android] Fix for TimePicker Dialog doesn't update the layout when rotating the device with dialog open by @HarishwaranVijayakumar in #31910 <details> <summary>🔧 Fixes</summary> - [[Android] TimePicker Dialog doesn't update the layout when rotating the device with dialog open](#31658) </details> - [Android, iOS] Fixed TimePicker FlowDirection Not Applied Across Platforms by @Dhivya-SF4094 in #30369 <details> <summary>🔧 Fixes</summary> - [TimePicker FlowDirection Not Working on All Platforms](#30192) </details> - [Windows] Fixed TimePicker CharacterSpacing issue by @SubhikshaSf4851 in #30533 <details> <summary>🔧 Fixes</summary> - [[Windows] TimePicker CharacterSpacing Property Not Working on Windows](#30199) </details> - [MacCatalyst] Fix DatePicker Opened/Closed events not being raised by @SubhikshaSf4851 in #34970 <details> <summary>🔧 Fixes</summary> - [[MacCatalyst] DatePicker Opened and Closed events are not raised on Mac platform](#34848) </details> ## Dialogalert - [Android] Fix AlertDialog, ActionSheet, and Prompt render with Material 2 styles when Material 3 is enabled by @HarishwaranVijayakumar in #35121 <details> <summary>🔧 Fixes</summary> - [[Android] AlertDialog, ActionSheet, and Prompt render with Material 2 styles when Material 3 is enabled](#35119) </details> ## Docs - docs: Add UITesting-Guide, ReleasePlanning, and ReleaseProcess to docs/README.md index by @PureWeen in #35195 - docs: Fix hardcoded path and add library overview in Essentials.AI README by @PureWeen in #35194 - docs: Update branch reference from net10.0 to net11.0 in DEVELOPMENT.md by @PureWeen in #35193 ## Drawing - Fix Path Rendering Issue Inside StackLayout When Margin Is Set by @Shalini-Ashokan in #28071 <details> <summary>🔧 Fixes</summary> - [Path does not render if it has Margin](#13801) </details> - Fixed FlowDirection property not working on Drawable control and GraphicsView by @Dhivya-SF4094 in #34557 <details> <summary>🔧 Fixes</summary> - [[Android, Windows, iOS, macOS] FlowDirection property not working on BoxView Control](#34402) </details> - [iOS & Mac] Fix image tile misalignment in GraphicsView ImagePaint by @SubhikshaSf4851 in #34935 <details> <summary>🔧 Fixes</summary> - [[iOS] Image resized with ResizeMode.Fit is not rendered correctly in GraphicsView](#34755) </details> - Fix Shadow does not honour Styles by @KarthikRajaKalaimani in #35081 <details> <summary>🔧 Fixes</summary> - [Shadow does not honour Styles](#19560) </details> ## Entry - [iOS/macCatalyst] Fix Entry and Editor BackgroundColor reset when set to null by @Shalini-Ashokan in #34741 <details> <summary>🔧 Fixes</summary> - [[iOS, Maccatalyst] Entry & Editor BackgroundColor not reset to Null](#34611) </details> - [Windows] Fix password Entry crash when setting text on empty field by @praveenkumarkarunanithi in #33891 <details> <summary>🔧 Fixes</summary> - [[WinUI] Password Obfuscation causes unhandled crash](#33334) </details> ## Essentials - [Essentials] Use mean sea level altitude on Android API 34+ by @KitKeen in #35097 <details> <summary>🔧 Fixes</summary> - [Add support for MslAltitudeMeters in Essentials Geolocation on Android](#27554) </details> ## Flyout - Fixed Flyout Not Displayed on Android When FlyoutWidth Is Set Only for Desktop via OnIdiom by @NanthiniMahalingam in #29028 <details> <summary>🔧 Fixes</summary> - [[Android] FlyoutWidth with OnIdiom shows no flyout](#13243) </details> - Revert "[Windows] Fix Flyout/Locked mode header collapse regression causing UI test failures on candidate branch" by @kubaflo in #35339 - Revert "Revert "[Windows] Fix Flyout/Locked mode header collapse regression causing UI test failures on candidate branch"" by @kubaflo in #35342 ## Flyoutpage - Fix [Android] Title of FlyOutPage is not updating anymore after showing a NonFlyOutPage by @KarthikRajaKalaimani in #34839 <details> <summary>🔧 Fixes</summary> - [[Android] Title of FlyOutPage is not updating anymore after showing a NonFlyOutPage](#33615) </details> ## Label - [iOS] Fix span Tap gesture on wrapped Label lines in iOS 26+ by @SubhikshaSf4851 in #34640 <details> <summary>🔧 Fixes</summary> - [[iOS]Span TapGestureRecognizer does not work on the second line of the span, if the span is wrapped to the next line](#34504) </details> ## Layout - Fixed Stacklayout is not rendered when clip is applied and StackLayout placed child to the Border control in iOS/ Mac platform by @KarthikRajaKalaimani in #33330 <details> <summary>🔧 Fixes</summary> - [[Mac/iOS] StackLayout fails to render content while applying Clip, and the layout is placed inside a Border with Background in .NET MAUI](#33241) </details> ## Map - Fix Changing Location on a Pin does nothing by @NirmalKumarYuvaraj in #30201 <details> <summary>🔧 Fixes</summary> - [[Maps] [Regression from Xamarin.Forms.Maps] Changing Location on a Pin does nothing](#12916) </details> ## Mediapicker - [iOS] Fix HEIC images picked via PickPhotosAsync not displayed by @HarishwaranVijayakumar in #34954 <details> <summary>🔧 Fixes</summary> - [[iOS] [Regression] HEIC images picked via PickPhotosAsync not displayed](#34953) </details> - [Android] Fix MediaPicker.PickPhotosAsync UnauthorizedAccessException on API 28 and below by @HarishwaranVijayakumar in #34981 <details> <summary>🔧 Fixes</summary> - [MediaPicker.PickPhotos fails to modify image, tries to load original source, fails to load source on Android 9.0](#34889) </details> ## Pages - [iOS] Fix ContentPage with ToolbarItem Clicked event leaks when presented as modal page by @devanathan-vaithiyanathan in #35009 <details> <summary>🔧 Fixes</summary> - [ContentPage with ToolbarItem Clicked event leaks when presented as modal page](#34892) </details> ## Platform - [Android] Fix OnBackButtonPressed not invoked for Shell by @Dhivya-SF4094 in #35150 <details> <summary>🔧 Fixes</summary> - [On Screen Back Button Does Not Fire OnBackButtonPressed in Android](#9095) </details> ## RadioButton - Fix RadioButtonGroup not working with ContentView by @Dhivya-SF4094 in #34781 <details> <summary>🔧 Fixes</summary> - [RadioButtonGroup not working with ContentView](#34759) </details> - [Windows] Fix for RadioButton BorderColor and BorderWidth not updated at runtime by @SyedAbdulAzeemSF4852 in #28335 <details> <summary>🔧 Fixes</summary> - [RadioButton Border color not working for focused visual state](#15806) </details> - [iOS] Fix RadioButton BackgroundColor bleeding outside CornerRadius by @SyedAbdulAzeemSF4852 in #34844 <details> <summary>🔧 Fixes</summary> - [[iOS] RadioButton BackgroundColor bleeds outside CornerRadius](#34842) </details> ## SafeArea - [iOS] Fix stale bottom safe area after changing SafeAreaEdges with keyboard open by @praveenkumarkarunanithi in #35083 <details> <summary>🔧 Fixes</summary> - [[iOS] ContentPage bottom has white space after changing SafeAreaEdges while keyboard is open](#34846) </details> ## ScrollView - [Windows] Fix Preserve ScrollView offsets when Orientation changes to Neither by @SubhikshaSf4851 in #34827 <details> <summary>🔧 Fixes</summary> - [[Windows] ScrollView offsets do not preserve when Orientation changes to Neither](#34671) </details> ## Searchbar - [iOS] Fix SearchBar unexpected left margin in iPad windowed mode on 26 Version by @SubhikshaSf4851 in #34704 <details> <summary>🔧 Fixes</summary> - [in iPad windowed mode SearchBar adds left margin equivaltent to SafeAreaInsets when placed inside grid](#34551) </details> ## Shell - [Windows] Fix for Shell.FlyoutBehavior="Flyout" forces the title height space above the tab bar even if the page title is empty by @BagavathiPerumal in #30382 <details> <summary>🔧 Fixes</summary> - [(Windows) Shell.FlyoutBehavior="Flyout" forces the title height space above the tab bar even if the page title is empty](#30254) </details> - Fix Shell flyout items scrolling behind FlyoutHeader on iOS by @Qythyx in #34936 <details> <summary>🔧 Fixes</summary> - [Shell flyout items scroll behind FlyoutHeader on iOS](#34925) </details> - [iOS, Mac] Fix Shell.CurrentState.Location stale in OnNavigated after GoToAsync by @Vignesh-SF3580 in #34880 <details> <summary>🔧 Fixes</summary> - [Shell.OnNavigated not called for route navigation](#34662) </details> - [iOS26]Fix BackButtonBehavior_IsEnabled_False_BackButtonDoesNotNavigate UITest fails by @devanathan-vaithiyanathan in #34890 <details> <summary>🔧 Fixes</summary> - [[iOS 26] BackButtonBehavior_IsEnabled_False_BackButtonDoesNotNavigate test fails with TimeoutException](#34771) </details> - [iOS] Fix Shell page memory leak when using TitleView with x:Name by @Shalini-Ashokan in #35082 <details> <summary>🔧 Fixes</summary> - [[iOS] Title view memory leak](#34975) </details> - [Material 3] Fix Material 2 color flash in AppBar when switching tabs for the first time by @Dhivya-SF4094 in #35117 <details> <summary>🔧 Fixes</summary> - [Material 3: AppBar briefly displays Material 2 colors when switching tabs for the first time](#35116) </details> - [Android] Fix Shell/TabbedPage "More" BottomSheet uses hard-coded M2 colors when Material3 is enabled by @HarishwaranVijayakumar in #35129 <details> <summary>🔧 Fixes</summary> - [[Android] Shell/TabbedPage "More" BottomSheet uses hard-coded M2 colors when Material3 is enabled](#35127) </details> - [Android] Shell: Fix top-tab unselected text visibility in Material 3 light theme by @SyedAbdulAzeemSF4852 in #35128 <details> <summary>🔧 Fixes</summary> - [[Android] Shell top-tab unselected text appears too faint in Material 3 light theme](#35125) </details> - Fix Shell.Items.Clear() memory leak by disconnecting child handlers on removal (#34898) by @Shalini-Ashokan in #35031 <details> <summary>🔧 Fixes</summary> - [Shell.Items.Clear() does not disconnect handlers correctly](#34898) </details> - [iOS&Mac] Fix Shell SearchHandler Query update on Initial load by @SubhikshaSf4851 in #35008 <details> <summary>🔧 Fixes</summary> - [[iOS&Mac] Shell SearchHandler Query not shown in search bar on initial load](#35005) </details> ## SwipeView - [iOS,MacCatalyst] Fix for SwipeView.Open() throwing an ArgumentException on the second programmatic call by @BagavathiPerumal in #34982 <details> <summary>🔧 Fixes</summary> - [[net 11.0][iOS,MacCatalyst] SwipeView.Open() throws ArgumentException on second programmatic call](#34917) </details> - [Android/iOS] Fix SwipeItem visibility change causing double command execution in Execute mode by @praveenkumarkarunanithi in #35087 <details> <summary>🔧 Fixes</summary> - [Changing visibility on an SwipeItem causes multiple items to be executed](#7580) </details> ## Switch - [iOS] Fix Switch ThumbColor reset on iOS 26+ theme changes. by @Shalini-Ashokan in #33953 <details> <summary>🔧 Fixes</summary> - [Switch ThumbColor not Initialized Using VisualStateManager on iOS Device](#33783) - [I9-On macOS 26.2, the "Animate scroll" button is white by default on iOS and Maccatalyst platforms.](#33767) </details> ## TabbedPage - [Windows] TabbedPage: Refresh layout when NavigationView size changes by @BagavathiPerumal in #26217 <details> <summary>🔧 Fixes</summary> - [TabbedPage - ScrollView not allowing scrolling when it should](#26103) - [TabbedPage App on resize hides page bottom content](#11402) - [Grid overflows child ContentPage of parent TabbedPage on initial load and when resizing on Windows](#20028) </details> - [Android] Material 3 Fixed BottomNavigationView overflowing in Tabbed page by @NirmalKumarYuvaraj in #35064 <details> <summary>🔧 Fixes</summary> - [[Android] Material3 - TabbedPage bottom tabs overflowing the contents](#35063) </details> - [Windows] Fix for Multiple Tabs Being Selected in WinUI TabbedPage by @SyedAbdulAzeemSF4852 in #33312 <details> <summary>🔧 Fixes</summary> - [WinUI TabbedPage can have multiple tabs selected](#31799) </details> ## Theming - [iOS] Fix StaticResource Hot Reload crash on iOS by @StephaneDelcroix in #35020 <details> <summary>🔧 Fixes</summary> - [The maui app quit and no errors in error list after editing ResourceDictionary XAML file on iOS Simulator with MAUI SR6 10.0.60](#35018) </details> ## Toolbar - [Windows] Fix for CS1061 build error caused by missing HasMenuBarContent property in MauiToolbar by @BagavathiPerumal in #35040 ## Tooling - Fix VisualStateGroups duplicate name crash with implicit styles (#34716) by @StephaneDelcroix in #34719 <details> <summary>🔧 Fixes</summary> - [SourceGen: VisualStateManager.VisualStateGroups causes 'Names must be unique' at startup](#34716) </details> ## WebView - Refactor the HybridWebView and properly support complex parameters by @mattleibow in #32491 - [Android] Fix WebView scrolling inside ScrollView by @Shalini-Ashokan in #33133 <details> <summary>🔧 Fixes</summary> - [[Android] WebView's content does not scroll when placed inside a ScrollView](#32971) </details> <details> <summary>🔧 Infrastructure (1)</summary> - [Windows] Fix Narrator announcing ContentView children twice when Description is set by @praveenkumarkarunanithi in #33979 <details> <summary>🔧 Fixes</summary> - [[Windows] SemanticProperties.Description announced twice when set on focusable container cell (Label inside)](#33373) </details> </details> <details> <summary>🧪 Testing (14)</summary> - [Testing] SafeArea Feature Matrix Test Cases for ContentPage by @TamilarasanSF4853 in #34877 - [Windows] Fix CollectionView ScrollTo related test cases failed in CI by @HarishwaranVijayakumar in #34907 <details> <summary>🔧 Fixes</summary> - [[Testing][Windows]CollectionView ScrollTo related test cases failed in CI](#34772) </details> - [Testing] Fixed Build error on inflight/ candidate PR 35234 by @HarishKumarSF4517 in #35241 - Fix CI for ValidateKeyboardRuntime_SwitchContainerToSoftInput_WhileKeyboardOpen test failure in May 4th Candidate by @devanathan-vaithiyanathan in #35307 - [Windows] Fix Flyout/Locked mode header collapse regression causing UI test failures on candidate branch by @BagavathiPerumal in #35312 - [iOS/macCatalyst] [Candidate Fix] Editor shadow and theme regression caused by BackgroundColor reset on initial handler connection by @Shalini-Ashokan in #35343 - [Testing] Fixed UI test image failure in PR 35234 - [30/03/2026] Candidate - 1 by @HarishKumarSF4517 in #35325 - [iOS] Fix ShellFeatureMatrix test failures on candidate branch by @Vignesh-SF3580 in #35346 - [Windows] Fix Issue29529VerifyPreviousPositionOnInsert test failure on candidate branch by @praveenkumarkarunanithi in #35398 - [Android] [Candidate Fix] Shell: Fix handler disconnect timing to preserve WebView navigation and memory leak fix by @Shalini-Ashokan in #35417 - [Testing]Revert 'Fix Preserve ScrollView offsets when Orientation changes to Neither' by @TamilarasanSF4853 in #35412 - [Windows] Fix VerifyAllIndicatorDotsShowShadowsWhenIndicatorSize test failure on candidate branch by @praveenkumarkarunanithi in #35458 - [Testing] Fixed test failure in PR 35234 - [05/08/2026] Candidate by @TamilarasanSF4853 in #35362 - [Testing] Fixed test failure in PR 35234 - [05/04/2026] Candidate - 3 by @TamilarasanSF4853 in #35639 </details> <details> <summary>📦 Other (6)</summary> - [UIKit] Avoid useless measure invalidation propagation cycles by @albyrock87 in #33459 - BindableObject property access micro-optimizations by @albyrock87 in #33584 - Extract filename from DisplayName and add extension if missing by @mattleibow in #35050 - [core] Add keyed-DI screenshot extensibility for 3rd-party platform backends by @Redth in #35096 <details> <summary>🔧 Fixes</summary> - [`ViewExtensions.CaptureAsync(IView)` and `IPlatformScreenshot` need extensibility for third-party platform backends](#34266) </details> - Fix MainThread throwing on custom platform backends by @Redth in #35070 <details> <summary>🔧 Fixes</summary> - [`MainThread.BeginInvokeOnMainThread` throws on custom platform backends - Common UI-thread marshaling pattern crashes; `Dispatcher` works but isn't the documented/recommended path](#34101) </details> - Tests: Add 11 missing UnitConverters unit tests by @PureWeen in #35191 </details> <details> <summary>📝 Issue References</summary> Fixes #7580, Fixes #9095, Fixes #11402, Fixes #12916, Fixes #13243, Fixes #13801, Fixes #15806, Fixes #19560, Fixes #19690, Fixes #19866, Fixes #20028, Fixes #26103, Fixes #26366, Fixes #27554, Fixes #29529, Fixes #29772, Fixes #30192, Fixes #30199, Fixes #30254, Fixes #31658, Fixes #31799, Fixes #32971, Fixes #33065, Fixes #33241, Fixes #33334, Fixes #33373, Fixes #33500, Fixes #33615, Fixes #33767, Fixes #33783, Fixes #34101, Fixes #34257, Fixes #34266, Fixes #34402, Fixes #34504, Fixes #34551, Fixes #34611, Fixes #34662, Fixes #34671, Fixes #34716, Fixes #34755, Fixes #34759, Fixes #34771, Fixes #34772, Fixes #34842, Fixes #34846, Fixes #34848, Fixes #34861, Fixes #34889, Fixes #34892, Fixes #34897, Fixes #34898, Fixes #34900, Fixes #34917, Fixes #34925, Fixes #34953, Fixes #34975, Fixes #35005, Fixes #35018, Fixes #35063, Fixes #35116, Fixes #35119, Fixes #35125, Fixes #35127 </details> **Full Changelog**: main...inflight/candidate
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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
On Windows, grouped CollectionView mutations rebuild WinUI’s internal flattened
ItemCollectionin stages while still raisingVectorChangedsynchronously mid-mutation. MAUI’sOnItemsVectorChangedhandler callsScrollIntoView(...)during this unstable state, re-entering WinUI while its projection is partially rebuilt, which triggers an uncatchableSTATUS_STOWED_EXCEPTION (0xc000027b)surfaced asCOMException.PR #24867 avoided the crash by unconditionally deferring
ScrollIntoViewthroughDispatcherQueue.TryEnqueue, but this introduced a regression in CarouselView (#29529 ), where the deferred callback overwrote the correct initialPositionwith stale values and triggered incorrectPositionChanged/CurrentItemChangedcascades.Description of Change
The fix scopes the deferred
ScrollIntoViewpath only to grouped CollectionView scenarios while preserving synchronous behavior for non-grouped controls like CarouselView.OnItemsVectorChangednow performs lifecycle and mode validation checks, skips unstableCollectionChange.Resetevents, and usesCollectionViewSource.IsSourceGroupedas the discriminator. Grouped sources deferScrollIntoViewIfNeeded()throughDispatcherQueue.TryEnqueueto avoid WinUI mid-mutation crashes, while non-grouped sources continue using the synchronous path to preserve existing CarouselView behavior and avoid reintroducing #29529 .The shared
ScrollIntoViewIfNeeded()helper revalidates lifecycle state, reads the latest projection fromCollectionViewSource.View, and applies the appropriate scroll behavior forKeepItemsInViewandKeepLastItemInViewmodes.Issues Fixed
Fixes
Issue29529VerifyPreviousPositionOnInserttest failure on candidate branchTested the behaviour in the following platforms