Fixes #4883. NullReferenceException in AdornmentView.Contains when Adornment is null#4884
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tig merged 2 commits intogui-cs:v2_developfrom Apr 6, 2026
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… is null AdornmentView has a parameter-less constructor (for AllViewsTester reflection support) that leaves Adornment = null. When such a view is placed inside a SuperView (e.g. the Themes UICatalog scenario creates AdornmentView/MarginView via reflection), moving the mouse over it caused a NullReferenceException at Adornment!.Thickness.Contains(...) because the null-forgiving ! operator did not prevent the dereference. Fix: add a guard clause returning false when Adornment is null, matching the existing pattern used in OnClearingViewport, OnDrawingText, and OnDrawingSubViews. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Fixes #4883.
Summary
AdornmentView.Containsthrows aNullReferenceExceptionwhenAdornmentis null. This happens when anAdornmentVieworMarginViewis created via its parameter-less constructor (e.g. by reflection in the Themes UICatalog scenario), placed inside aSuperView, and the mouse is moved over it.The
Containsoverride correctly guards againstAdornment?.Parentbeing null and falls back toSuperView— but onceSuperViewis non-null, execution reachesAdornment!.Thickness.Contains(...)where the null-forgiving!operator suppresses the compiler warning without preventing the runtime crash.Fix
Added a null guard for
Adornmentbefore the thickness check, consistent with the existing pattern inOnClearingViewport,OnDrawingText, andOnDrawingSubViews.Testing
Added a regression test in
Tests/UnitTestsParallelizable/ViewBase/Adornment/AdornmentViewTests.cs.