Fix TabView windowing sample launch failure - #2160
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Replace Win32WindowHelper (P/Invoke with static fields) with the modern WindowHelper.SetWindowMinSize (OverlappedPresenter API) for setting minimum window size. The Win32WindowHelper caused crashes due to static oldWndProc/newWndProc fields being shared across multiple windows. The minimum window size is now set in the Loaded event handler where XamlRoot is available, rather than before window activation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Marcel W. (marcelwgn)
approved these changes
Apr 18, 2026
Marcel W. (marcelwgn)
enabled auto-merge (squash)
April 18, 2026 13:14
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/azp run |
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Description
Note
This PR was generated with the assistance of GitHub Copilot (AI). All changes should be reviewed carefully.
Fixes #2154
The "Click here to launch the sample" button on the TabView page fails to open the windowing sample window.
Root cause
TabViewWindowingSamplePageusesWin32WindowHelperto set minimum window size via P/Invoke (SetWindowLongPtrto subclass the window procedure). This class uses static fields foroldWndProcandnewWndProc, which causes crashes when multiple windows are involved — the same bug that PR #2007 fixed for other pages by introducingWindowHelper.SetWindowMinSize.Fix
Win32WindowHelper.SetWindowMinMaxSize()withWindowHelper.SetWindowMinSize()(usesOverlappedPresenter.PreferredMinimumWidth/Height)Loadedevent handler whereXamlRootis availableSetupWindowMinSizemethod and its callersDataIdentifierconstant andWin32WindowHelperfieldValidation
dotnet build WinUIGallery\WinUIGallery.csproj /p:Platform=x64— 0 errors