feat(BorderBeam, Splash): update layout and introduce version tags in showcase components

controlgallery/AtomUIGallery/GeneratedFiles/AtomUI.Generator/AtomUI.Generator.LanguageGenerator/LanguageProviderPool.g.cs

@@ -1233,7 +1233,7 @@ namespace AtomUI.Theme.Language
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.BasicDescription] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.BasicDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.BasicTitle] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.BasicTitle;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentCategory] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.ComponentCategory;
-                dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentStatusPreview] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.ComponentStatusPreview;
+                dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentIntroducedVersion] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.ComponentIntroducedVersion;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorCardDescription] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.CustomizedColorCardDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorDescription] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.CustomizedColorDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorTitle] = global::AtomUIGallery.ShowCases.BorderBeam.en_US.CustomizedColorTitle;
@@ -1299,7 +1299,7 @@ namespace AtomUI.Theme.Language
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.BasicDescription] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.BasicDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.BasicTitle] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.BasicTitle;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentCategory] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.ComponentCategory;
-                dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentStatusPreview] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.ComponentStatusPreview;
+                dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentIntroducedVersion] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.ComponentIntroducedVersion;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorCardDescription] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.CustomizedColorCardDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorDescription] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.CustomizedColorDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorTitle] = global::AtomUIGallery.ShowCases.BorderBeam.zh_CN.CustomizedColorTitle;
@@ -1365,7 +1365,7 @@ namespace AtomUI.Theme.Language
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.BasicDescription] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.BasicDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.BasicTitle] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.BasicTitle;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentCategory] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.ComponentCategory;
-                dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentStatusPreview] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.ComponentStatusPreview;
+                dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.ComponentIntroducedVersion] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.ComponentIntroducedVersion;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorCardDescription] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.CustomizedColorCardDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorDescription] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.CustomizedColorDescription;
                 dictionary[global::AtomUIGallery.Localization.BorderBeamShowCaseLangResourceKind.CustomizedColorTitle] = global::AtomUIGallery.ShowCases.BorderBeam.zh_TW.CustomizedColorTitle;
@@ -18568,6 +18568,7 @@ namespace AtomUI.Theme.Language
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.BasicDescription] = global::AtomUIGallery.ShowCases.Splash.en_US.BasicDescription;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.BasicTitle] = global::AtomUIGallery.ShowCases.Splash.en_US.BasicTitle;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentCategory] = global::AtomUIGallery.ShowCases.Splash.en_US.ComponentCategory;
+                dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentIntroducedVersion] = global::AtomUIGallery.ShowCases.Splash.en_US.ComponentIntroducedVersion;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentStatusPreview] = global::AtomUIGallery.ShowCases.Splash.en_US.ComponentStatusPreview;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComposedDescription] = global::AtomUIGallery.ShowCases.Splash.en_US.ComposedDescription;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComposedTitle] = global::AtomUIGallery.ShowCases.Splash.en_US.ComposedTitle;
@@ -18681,6 +18682,7 @@ namespace AtomUI.Theme.Language
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.BasicDescription] = global::AtomUIGallery.ShowCases.Splash.zh_CN.BasicDescription;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.BasicTitle] = global::AtomUIGallery.ShowCases.Splash.zh_CN.BasicTitle;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentCategory] = global::AtomUIGallery.ShowCases.Splash.zh_CN.ComponentCategory;
+                dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentIntroducedVersion] = global::AtomUIGallery.ShowCases.Splash.zh_CN.ComponentIntroducedVersion;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentStatusPreview] = global::AtomUIGallery.ShowCases.Splash.zh_CN.ComponentStatusPreview;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComposedDescription] = global::AtomUIGallery.ShowCases.Splash.zh_CN.ComposedDescription;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComposedTitle] = global::AtomUIGallery.ShowCases.Splash.zh_CN.ComposedTitle;
@@ -18794,6 +18796,7 @@ namespace AtomUI.Theme.Language
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.BasicDescription] = global::AtomUIGallery.ShowCases.Splash.zh_TW.BasicDescription;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.BasicTitle] = global::AtomUIGallery.ShowCases.Splash.zh_TW.BasicTitle;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentCategory] = global::AtomUIGallery.ShowCases.Splash.zh_TW.ComponentCategory;
+                dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentIntroducedVersion] = global::AtomUIGallery.ShowCases.Splash.zh_TW.ComponentIntroducedVersion;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComponentStatusPreview] = global::AtomUIGallery.ShowCases.Splash.zh_TW.ComponentStatusPreview;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComposedDescription] = global::AtomUIGallery.ShowCases.Splash.zh_TW.ComposedDescription;
                 dictionary[global::AtomUIGallery.Localization.SplashShowCaseLangResourceKind.ComposedTitle] = global::AtomUIGallery.ShowCases.Splash.zh_TW.ComposedTitle;

controlgallery/AtomUIGallery/GeneratedFiles/AtomUI.Generator/AtomUI.Generator.LanguageGenerator/LanguageResourceConst.g.cs

@@ -387,7 +387,7 @@ namespace AtomUIGallery.Localization
         BasicDescription,
         BasicTitle,
         ComponentCategory,
-        ComponentStatusPreview,
+        ComponentIntroducedVersion,
         CustomizedColorCardDescription,
         CustomizedColorDescription,
         CustomizedColorTitle,
@@ -5841,6 +5841,7 @@ namespace AtomUIGallery.Localization
         BasicDescription,
         BasicTitle,
         ComponentCategory,
+        ComponentIntroducedVersion,
         ComponentStatusPreview,
         ComposedDescription,
         ComposedTitle,

controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Localization/en_US.cs

@@ -10,7 +10,7 @@ internal partial class en_US : LanguageProvider
     public const string ScenarioApi = "API";
     public const string ScenarioDesignToken = "Design Token";
     public const string ComponentCategory = "Other";
-    public const string ComponentStatusPreview = "v6.0.5";
+    public const string ComponentIntroducedVersion = "v6.0.5";
     public const string PageSubtitle = "Draw an animated highlight along a container boundary.";
     public const string PageDescription = "BorderBeam wraps a content control and renders a non-interactive beam on its border. It is decorative, follows theme motion settings, and can use a solid color or gradient stops.";
     public const string InfoNamespaceLabel = "Namespace:";

controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Localization/zh_CN.cs

@@ -10,7 +10,7 @@ internal partial class zh_CN : LanguageProvider
     public const string ScenarioApi = "API";
     public const string ScenarioDesignToken = "设计变量";
     public const string ComponentCategory = "其他";
-    public const string ComponentStatusPreview = "v6.0.5";
+    public const string ComponentIntroducedVersion = "v6.0.5";
     public const string PageSubtitle = "沿容器边界绘制动态高光。";
     public const string PageDescription = "BorderBeam 包裹一个内容控件，并在其边界上渲染不参与交互的流光层。它只承担装饰性强调，遵守主题动效设置，并支持单色或渐变停靠点。";
     public const string InfoNamespaceLabel = "命名空间:";

controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Localization/zh_TW.cs

@@ -10,7 +10,7 @@ internal partial class zh_TW : LanguageProvider
     public const string ScenarioApi = "API";
     public const string ScenarioDesignToken = "設計變數";
     public const string ComponentCategory = "其他";
-    public const string ComponentStatusPreview = "v6.0.5";
+    public const string ComponentIntroducedVersion = "v6.0.5";
     public const string PageSubtitle = "沿容器邊界繪製動態高光。";
     public const string PageDescription = "BorderBeam 包裹一個內容控制項，並在其邊界上渲染不參與互動的流光層。它只承擔裝飾性強調，遵守主題動效設定，並支援單色或漸變停靠點。";
     public const string InfoNamespaceLabel = "命名空間:";

controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Views/BorderBeamShowCase.axaml

@@ -11,20 +11,27 @@
                 <StackPanel Margin="28,24,28,18"
                             Spacing="16">
                     <StackPanel Spacing="6">
-                        <StackPanel Orientation="Horizontal"
-                                    Spacing="10"
-                                    VerticalAlignment="Center">
-                            <atom:TextBlock Text="BorderBeam"
+                        <Grid ColumnDefinitions="Auto,*"
+                              VerticalAlignment="Center">
+                            <atom:TextBlock Grid.Column="0"
+                                            Text="BorderBeam"
                                             FontSize="26"
                                             FontWeight="Bold"
                                             VerticalAlignment="Center" />
-                            <atom:Tag Text="{gallery:BorderBeamShowCaseLangResource ComponentCategory}"
-                                      TagColor="geekblue"
-                                      VerticalAlignment="Center" />
-                            <atom:Tag Text="{gallery:BorderBeamShowCaseLangResource ComponentStatusPreview}"
-                                      TagColor="processing"
-                                      VerticalAlignment="Center" />
-                        </StackPanel>
+                            <WrapPanel Grid.Column="1"
+                                       Margin="10,0,0,0"
+                                       ItemSpacing="10"
+                                       LineSpacing="6"
+                                       VerticalAlignment="Center">
+                                <atom:Tag Text="{gallery:BorderBeamShowCaseLangResource ComponentCategory}"
+                                          TagColor="blue"
+                                          VerticalAlignment="Center" />
+                                <atom:Tag Text="{gallery:BorderBeamShowCaseLangResource ComponentIntroducedVersion}"
+                                          TagColor="blue"
+                                          IsBordered="False"
+                                          VerticalAlignment="Center" />
+                            </WrapPanel>
+                        </Grid>
                         <atom:TextBlock Text="{gallery:BorderBeamShowCaseLangResource PageSubtitle}"
                                         FontSize="15"
                                         Foreground="{atom:SharedTokenResource ColorTextSecondary}" />

controlgallery/AtomUIGallery/ShowCases/Other/Splash/Localization/en_US.cs

@@ -11,6 +11,7 @@ internal partial class en_US : LanguageProvider
     public const string ScenarioDesignToken = "Design Token";
     public const string ComponentCategory = "Other";
     public const string ComponentStatusPreview = "Preview";
+    public const string ComponentIntroducedVersion = "v6.0.7";
     public const string PageSubtitle = "Present desktop startup progress before the main workspace is ready.";
     public const string PageDescription = "Splash combines a compact branded surface, loading indicator, determinate progress, status copy, and optional footer. The service API can host it in a borderless startup window, while the visual control can be previewed directly in Gallery.";
     public const string InfoNamespaceLabel = "Namespace:";

controlgallery/AtomUIGallery/ShowCases/Other/Splash/Localization/zh_CN.cs

@@ -11,6 +11,7 @@ internal partial class zh_CN : LanguageProvider
     public const string ScenarioDesignToken = "Design Token";
     public const string ComponentCategory = "其他";
     public const string ComponentStatusPreview = "预览";
+    public const string ComponentIntroducedVersion = "v6.0.7";
     public const string PageSubtitle = "在主工作区准备完成前呈现桌面启动进度。";
     public const string PageDescription = "Splash 组合紧凑的品牌面板、加载指示、确定进度、状态文案和可选页脚。服务 API 可将它托管在无边框启动窗口中，视觉控件也可以直接在 Gallery 中预览。";
     public const string InfoNamespaceLabel = "命名空间：";

controlgallery/AtomUIGallery/ShowCases/Other/Splash/Localization/zh_TW.cs

@@ -11,6 +11,7 @@ internal partial class zh_TW : LanguageProvider
     public const string ScenarioDesignToken = "Design Token";
     public const string ComponentCategory = "其他";
     public const string ComponentStatusPreview = "預覽";
+    public const string ComponentIntroducedVersion = "v6.0.7";
     public const string PageSubtitle = "在主工作區準備完成前呈現桌面啟動進度。";
     public const string PageDescription = "Splash 組合緊湊的品牌面板、載入指示、確定進度、狀態文案和可選頁腳。服務 API 可將它託管在無邊框啟動視窗中，視覺控件也可以直接在 Gallery 中預覽。";
     public const string InfoNamespaceLabel = "命名空間：";

controlgallery/AtomUIGallery/ShowCases/Other/Splash/Views/SplashShowCase.axaml

@@ -11,20 +11,30 @@
                 <StackPanel Margin="28,24,28,18"
                             Spacing="16">
                     <StackPanel Spacing="6">
-                        <StackPanel Orientation="Horizontal"
-                                    Spacing="10"
-                                    VerticalAlignment="Center">
-                            <atom:TextBlock Text="Splash"
+                        <Grid ColumnDefinitions="Auto,*"
+                              VerticalAlignment="Center">
+                            <atom:TextBlock Grid.Column="0"
+                                            Text="Splash"
                                             FontSize="26"
                                             FontWeight="Bold"
                                             VerticalAlignment="Center" />
-                            <atom:Tag Text="{gallery:SplashShowCaseLangResource ComponentCategory}"
-                                      TagColor="geekblue"
-                                      VerticalAlignment="Center" />
-                            <atom:Tag Text="{gallery:SplashShowCaseLangResource ComponentStatusPreview}"
-                                      TagColor="processing"
-                                      VerticalAlignment="Center" />
-                        </StackPanel>
+                            <WrapPanel Grid.Column="1"
+                                       Margin="10,0,0,0"
+                                       ItemSpacing="10"
+                                       LineSpacing="6"
+                                       VerticalAlignment="Center">
+                                <atom:Tag Text="{gallery:SplashShowCaseLangResource ComponentCategory}"
+                                          TagColor="blue"
+                                          VerticalAlignment="Center" />
+                                <atom:Tag Text="{gallery:SplashShowCaseLangResource ComponentStatusPreview}"
+                                          TagColor="processing"
+                                          VerticalAlignment="Center" />
+                                <atom:Tag Text="{gallery:SplashShowCaseLangResource ComponentIntroducedVersion}"
+                                          TagColor="blue"
+                                          IsBordered="False"
+                                          VerticalAlignment="Center" />
+                            </WrapPanel>
+                        </Grid>
                         <atom:TextBlock Text="{gallery:SplashShowCaseLangResource PageSubtitle}"
                                         FontSize="15"
                                         Foreground="{atom:SharedTokenResource ColorTextSecondary}" />

src/AtomUI.Toolkits.GalleryBase/Controls/GalleryCodeViewer.cs

@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using System.Collections.ObjectModel;
 using AtomUI.Controls;
 using AtomUI.Theme;
 using Avalonia;
@@ -8,10 +9,15 @@ using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Layout;
 using Avalonia.Styling;
+using Avalonia.Threading;
 using Avalonia.VisualTree;
 using AvaloniaEdit;
+using AvaloniaEdit.Document;
 using AvaloniaEdit.TextMate;
+using TextMateSharp.Model;
 using TextMateSharp.Grammars;
+using TextMateSharp.Registry;
+using TextMateSharp.Themes;
 using AtomUIContextMenu = AtomUI.Desktop.Controls.ContextMenu;
 using AtomUIMenuItem = AtomUI.Desktop.Controls.MenuItem;
 
@@ -42,13 +48,14 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
         IsEnabled = false
     };
 
-    private TextMate.Installation? _textMateInstallation;
+    private GalleryTextMateInstallation? _textMateInstallation;
     private RegistryOptions? _registryOptions;
     private ScrollBar? _horizontalScrollBar;
     private Application? _subscribedApplication;
     private IThemeManager? _subscribedThemeManager;
     private IDisposable? _themeVariantSubscription;
     private ThemeName? _currentSyntaxTheme;
+    private bool _isHorizontalScrollBarInsetUpdatePending;
     private bool _isUpdatingScrollBarInset;
     private bool _isDisposed;
 
@@ -56,7 +63,6 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
     {
         InitializeComponent();
         _editor = this.FindControl<TextEditor>("PART_Editor")!;
-        _editor.LayoutUpdated += HandleEditorLayoutUpdated;
         _editor.TextArea.SelectionChanged += HandleEditorSelectionChanged;
         ActualThemeVariantChanged += HandleActualThemeVariantChanged;
         ConfigureEditorContextMenu();
@@ -107,7 +113,7 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
         _textMateInstallation = null;
         _registryOptions      = null;
         ReleaseThemeVariantSubscriptions();
-        _editor.LayoutUpdated -= HandleEditorLayoutUpdated;
+        CancelHorizontalScrollBarGutterInsetUpdate();
         _editor.TextArea.SelectionChanged -= HandleEditorSelectionChanged;
         _editor.Document      = null;
         _copyMenuItem.Click -= HandleCopyMenuItemClick;
@@ -136,7 +142,7 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
         else if (change.Property == ShowLineNumbersProperty)
         {
             _editor.ShowLineNumbers = ShowLineNumbers;
-            UpdateHorizontalScrollBarGutterInset();
+            RequestHorizontalScrollBarGutterInsetUpdate();
         }
         else if (change.Property == LightSyntaxThemeProperty ||
                  change.Property == DarkSyntaxThemeProperty)
@@ -150,16 +156,19 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
         base.OnAttachedToVisualTree(e);
         SubscribeThemeVariantChanges();
         ApplySyntaxTheme();
+        RequestHorizontalScrollBarGutterInsetUpdate();
     }
 
     protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
     {
+        CancelHorizontalScrollBarGutterInsetUpdate();
         ReleaseThemeVariantSubscriptions();
         base.OnDetachedFromVisualTree(e);
     }
 
     private void HandleEditorLayoutUpdated(object? sender, EventArgs e)
     {
+        CancelHorizontalScrollBarGutterInsetUpdate();
         UpdateHorizontalScrollBarGutterInset();
     }
 
@@ -201,12 +210,33 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
         ApplySyntaxTheme();
     }
 
+    private void RequestHorizontalScrollBarGutterInsetUpdate()
+    {
+        if (_isDisposed || _isHorizontalScrollBarInsetUpdatePending)
+        {
+            return;
+        }
+
+        _isHorizontalScrollBarInsetUpdatePending = true;
+        _editor.LayoutUpdated += HandleEditorLayoutUpdated;
+    }
+
+    private void CancelHorizontalScrollBarGutterInsetUpdate()
+    {
+        if (!_isHorizontalScrollBarInsetUpdatePending)
+        {
+            return;
+        }
+
+        _isHorizontalScrollBarInsetUpdatePending = false;
+        _editor.LayoutUpdated -= HandleEditorLayoutUpdated;
+    }
+
     private void UpdateHorizontalScrollBarGutterInset()
     {
-        // This runs from LayoutUpdated. Mutating the scroll bar Margin below triggers another
-        // layout pass, which re-enters here. Without this guard, dragging a selection past the
-        // right edge (which auto-scrolls and fires LayoutUpdated continuously) spins the layout
-        // system forever and hangs the UI thread.
+        // Mutating the scroll bar Margin triggers another layout pass, so this method must only
+        // run from the one-shot request path above. Drag selection auto-scroll produces repeated
+        // LayoutUpdated ticks, and a permanent handler can spin the UI thread.
         if (_isUpdatingScrollBarInset)
         {
             return;
@@ -277,6 +307,7 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
     private void UpdateText()
     {
         _editor.Text = CodeText ?? string.Empty;
+        RequestHorizontalScrollBarGutterInsetUpdate();
     }
 
     private void ConfigureEditorContextMenu()
@@ -290,7 +321,7 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
 
     private void UpdateCopyMenuItemState()
     {
-        _copyMenuItem.IsEnabled = !string.IsNullOrEmpty(GetSelectedCodeText());
+        _copyMenuItem.IsEnabled = !_editor.TextArea.Selection.IsEmpty;
     }
 
     private string GetSelectedCodeText()
@@ -331,7 +362,7 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
 
         var syntaxTheme = ResolveSyntaxTheme();
         _registryOptions = new RegistryOptions(syntaxTheme);
-        _textMateInstallation = _editor.InstallTextMate(_registryOptions);
+        _textMateInstallation = new GalleryTextMateInstallation(_editor, _registryOptions);
         _currentSyntaxTheme = syntaxTheme;
     }
 
@@ -443,4 +474,439 @@ public sealed partial class GalleryCodeViewer : UserControl, IDisposable
 
         return _registryOptions?.GetScopeByExtension(extension);
     }
+
+    private sealed class GalleryTextMateInstallation : IDisposable
+    {
+        private readonly object _lock = new();
+        private readonly Registry _textMateRegistry;
+        private readonly TextEditor _editor;
+        private readonly TextMateColoringTransformer _transformer;
+        private readonly bool _ownsTransformer;
+        private Action<Exception>? _exceptionHandler;
+        private GalleryTextEditorModel? _editorModel;
+        private IGrammar? _grammar;
+        private TMModel? _tmModel;
+        private ReadOnlyDictionary<string, string>? _themeColorsDictionary;
+        private bool _isDisposed;
+
+        public GalleryTextMateInstallation(TextEditor editor,
+                                           IRegistryOptions registryOptions,
+                                           Action<Exception>? exceptionHandler = null)
+        {
+            RegistryOptions = registryOptions ?? throw new ArgumentNullException(nameof(registryOptions));
+            _editor = editor ?? throw new ArgumentNullException(nameof(editor));
+            _exceptionHandler = exceptionHandler;
+            _textMateRegistry = new Registry(registryOptions);
+            _transformer = _editor.TextArea.TextView.LineTransformers
+                                  .OfType<TextMateColoringTransformer>()
+                                  .FirstOrDefault() ??
+                           new TextMateColoringTransformer(_editor.TextArea.TextView, _exceptionHandler);
+
+            if (!_editor.TextArea.TextView.LineTransformers.Contains(_transformer))
+            {
+                _editor.TextArea.TextView.LineTransformers.Add(_transformer);
+                _ownsTransformer = true;
+            }
+
+            SetTheme(registryOptions.GetDefaultTheme());
+            _editor.DocumentChanged += HandleEditorDocumentChanged;
+            HandleEditorDocumentChanged(_editor, EventArgs.Empty);
+        }
+
+        public IRegistryOptions RegistryOptions { get; }
+
+        public void SetGrammar(string scopeName)
+        {
+            ThrowIfDisposed();
+            lock (_lock)
+            {
+                ThrowIfDisposed();
+                SetGrammarInternal(_textMateRegistry.LoadGrammar(scopeName));
+                ForceTokenizeDocument();
+            }
+            _editor.TextArea.TextView.Redraw();
+        }
+
+        public bool TryGetThemeColor(string colorKey, out string? colorString)
+        {
+            ThrowIfDisposed();
+            return (_themeColorsDictionary ?? throw new ObjectDisposedException(nameof(GalleryTextMateInstallation)))
+                .TryGetValue(colorKey, out colorString);
+        }
+
+        public void SetTheme(IRawTheme theme)
+        {
+            ThrowIfDisposed();
+            lock (_lock)
+            {
+                ThrowIfDisposed();
+                _textMateRegistry.SetTheme(theme);
+                var textMateTheme = _textMateRegistry.GetTheme();
+                _transformer.SetTheme(textMateTheme);
+                _tmModel?.InvalidateLine(0);
+                _editorModel?.InvalidateViewPortLines();
+                _themeColorsDictionary = textMateTheme.GetGuiColorDictionary();
+            }
+        }
+
+        public void Dispose()
+        {
+            if (_isDisposed)
+            {
+                return;
+            }
+
+            GalleryTextEditorModel? editorModel;
+            TMModel? tmModel;
+            lock (_lock)
+            {
+                if (_isDisposed)
+                {
+                    return;
+                }
+
+                _isDisposed = true;
+                editorModel = _editorModel;
+                _editorModel = null;
+                tmModel = _tmModel;
+                _tmModel = null;
+                _grammar = null;
+                _themeColorsDictionary = null;
+                _exceptionHandler = null;
+            }
+
+            _editor.DocumentChanged -= HandleEditorDocumentChanged;
+            editorModel?.Dispose();
+            DisposeTMModel(tmModel);
+
+            if (_ownsTransformer)
+            {
+                _editor.TextArea.TextView.LineTransformers.Remove(_transformer);
+                _transformer.Dispose();
+            }
+            else
+            {
+                _transformer.SetModel(null, null);
+            }
+        }
+
+        private void HandleEditorDocumentChanged(object? sender, EventArgs e)
+        {
+            if (_isDisposed || _editor.Document is null)
+            {
+                return;
+            }
+
+            lock (_lock)
+            {
+                if (_isDisposed || _editor.Document is null)
+                {
+                    return;
+                }
+
+                try
+                {
+                    _editorModel?.Dispose();
+                    DisposeTMModel(_tmModel);
+                    _editorModel = new GalleryTextEditorModel(
+                        _editor.TextArea.TextView,
+                        _editor.Document,
+                        _exceptionHandler);
+                    _tmModel = new TMModel(_editorModel);
+                    _tmModel.SetGrammar(_grammar);
+                    _transformer.SetModel(_editor.Document, _tmModel);
+                    _tmModel.AddModelTokensChangedListener(_transformer);
+                    ForceTokenizeDocument();
+                }
+                catch (Exception ex)
+                {
+                    _exceptionHandler?.Invoke(ex);
+                }
+            }
+        }
+
+        private void SetGrammarInternal(IGrammar grammar)
+        {
+            _grammar = grammar;
+            _transformer.SetGrammar(_grammar);
+        }
+
+        private void ForceTokenizeDocument()
+        {
+            _editorModel?.ForceTokenizeAllLines();
+        }
+
+        private void ThrowIfDisposed()
+        {
+            if (_isDisposed)
+            {
+                throw new ObjectDisposedException(nameof(GalleryTextMateInstallation));
+            }
+        }
+
+        private void DisposeTMModel(TMModel? tmModel)
+        {
+            if (tmModel is null)
+            {
+                return;
+            }
+
+            tmModel.RemoveModelTokensChangedListener(_transformer);
+            tmModel.Dispose();
+        }
+    }
+
+    private sealed class GalleryTextEditorModel : AbstractLineList, IDisposable
+    {
+        private readonly TextDocument _document;
+        private readonly AvaloniaEdit.Rendering.TextView _textView;
+        private readonly Action<Exception>? _exceptionHandler;
+        private DocumentSnapshot _documentSnapshot;
+        private InvalidLineRange? _invalidRange;
+        private bool _isViewportTokenizationPending;
+        private int _pendingViewportStartLine = -1;
+        private int _pendingViewportEndLine = -1;
+        private bool _isDisposed;
+
+        public GalleryTextEditorModel(AvaloniaEdit.Rendering.TextView textView,
+                                      TextDocument document,
+                                      Action<Exception>? exceptionHandler)
+        {
+            _textView = textView;
+            _document = document;
+            _exceptionHandler = exceptionHandler;
+            _documentSnapshot = new DocumentSnapshot(_document);
+            for (var i = 0; i < _document.LineCount; i++)
+            {
+                AddLine(i);
+            }
+
+            _document.Changing += HandleDocumentChanging;
+            _document.Changed += HandleDocumentChanged;
+            _document.UpdateFinished += HandleDocumentUpdateFinished;
+            _textView.ScrollOffsetChanged += HandleTextViewScrollOffsetChanged;
+        }
+
+        public override void Dispose()
+        {
+            if (_isDisposed)
+            {
+                return;
+            }
+
+            _isDisposed = true;
+            _document.Changing -= HandleDocumentChanging;
+            _document.Changed -= HandleDocumentChanged;
+            _document.UpdateFinished -= HandleDocumentUpdateFinished;
+            _textView.ScrollOffsetChanged -= HandleTextViewScrollOffsetChanged;
+        }
+
+        public override void UpdateLine(int lineIndex)
+        {
+        }
+
+        public override int GetNumberOfLines()
+        {
+            return _documentSnapshot.LineCount;
+        }
+
+        public override LineText GetLineTextIncludingTerminators(int lineIndex)
+        {
+            return _documentSnapshot.GetLineTextIncludingTerminatorAsMemory(lineIndex);
+        }
+
+        public override int GetLineLength(int lineIndex)
+        {
+            return _documentSnapshot.GetLineLength(lineIndex);
+        }
+
+        public void InvalidateViewPortLines()
+        {
+            if (_textView.VisualLinesValid && _textView.VisualLines.Count != 0)
+            {
+                InvalidateLineRange(GetFirstVisibleLineIndex(), GetLastVisibleLineIndex());
+            }
+        }
+
+        public void ForceTokenizeAllLines()
+        {
+            var lineCount = _documentSnapshot.LineCount;
+            if (lineCount > 0)
+            {
+                ForceTokenization(0, lineCount - 1);
+            }
+        }
+
+        private void HandleTextViewScrollOffsetChanged(object? sender, EventArgs e)
+        {
+            try
+            {
+                RequestViewportTokenization();
+            }
+            catch (Exception ex)
+            {
+                _exceptionHandler?.Invoke(ex);
+            }
+        }
+
+        private void RequestViewportTokenization()
+        {
+            if (_isDisposed || !_textView.VisualLinesValid || _textView.VisualLines.Count == 0)
+            {
+                return;
+            }
+
+            var startLine = GetFirstVisibleLineIndex();
+            var endLine = GetLastVisibleLineIndex();
+            if (_pendingViewportStartLine < 0)
+            {
+                _pendingViewportStartLine = startLine;
+                _pendingViewportEndLine = endLine;
+            }
+            else
+            {
+                _pendingViewportStartLine = Math.Min(_pendingViewportStartLine, startLine);
+                _pendingViewportEndLine = Math.Max(_pendingViewportEndLine, endLine);
+            }
+
+            if (_isViewportTokenizationPending)
+            {
+                return;
+            }
+
+            _isViewportTokenizationPending = true;
+            Avalonia.Threading.Dispatcher.UIThread.Post(
+                ProcessPendingViewportTokenization,
+                DispatcherPriority.Background);
+        }
+
+        private void ProcessPendingViewportTokenization()
+        {
+            if (_isDisposed)
+            {
+                return;
+            }
+
+            var startLine = _pendingViewportStartLine;
+            var endLine = _pendingViewportEndLine;
+            _pendingViewportStartLine = -1;
+            _pendingViewportEndLine = -1;
+            _isViewportTokenizationPending = false;
+            if (startLine >= 0 && endLine >= startLine)
+            {
+                ForceTokenization(startLine, endLine);
+            }
+        }
+
+        private void HandleDocumentChanging(object? sender, DocumentChangeEventArgs e)
+        {
+            try
+            {
+                if (e.RemovalLength <= 0)
+                {
+                    return;
+                }
+
+                var startLine = _document.GetLineByOffset(e.Offset).LineNumber - 1;
+                var endLine = _document.GetLineByOffset(e.Offset + e.RemovalLength).LineNumber - 1;
+                for (var line = endLine; line > startLine; line--)
+                {
+                    RemoveLine(line);
+                }
+                _documentSnapshot.RemoveLines(startLine, endLine);
+            }
+            catch (Exception ex)
+            {
+                _exceptionHandler?.Invoke(ex);
+            }
+        }
+
+        private void HandleDocumentChanged(object? sender, DocumentChangeEventArgs e)
+        {
+            try
+            {
+                var startLine = _document.GetLineByOffset(e.Offset).LineNumber - 1;
+                var endLine = startLine;
+                if (e.InsertionLength > 0)
+                {
+                    endLine = _document.GetLineByOffset(e.Offset + e.InsertionLength).LineNumber - 1;
+                    for (var line = startLine; line < endLine; line++)
+                    {
+                        AddLine(line);
+                    }
+                }
+
+                _documentSnapshot.Update(e);
+                SetInvalidRange(startLine == 0 ? startLine : startLine - 1, endLine);
+            }
+            catch (Exception ex)
+            {
+                _exceptionHandler?.Invoke(ex);
+            }
+        }
+
+        private void SetInvalidRange(int startLine, int endLine)
+        {
+            if (!_document.IsInUpdate)
+            {
+                InvalidateLineRange(startLine, endLine);
+            }
+            else if (_invalidRange is null)
+            {
+                _invalidRange = new InvalidLineRange(startLine, endLine);
+            }
+            else
+            {
+                _invalidRange.SetInvalidRange(startLine, endLine);
+            }
+        }
+
+        private void HandleDocumentUpdateFinished(object? sender, EventArgs e)
+        {
+            if (_invalidRange is null)
+            {
+                return;
+            }
+
+            try
+            {
+                var startLine = Math.Clamp(_invalidRange.StartLine, 0, _documentSnapshot.LineCount - 1);
+                var endLine = Math.Clamp(_invalidRange.EndLine, 0, _documentSnapshot.LineCount - 1);
+                InvalidateLineRange(startLine, endLine);
+            }
+            finally
+            {
+                _invalidRange = null;
+            }
+        }
+
+        private int GetFirstVisibleLineIndex()
+        {
+            return _textView.VisualLines[0].FirstDocumentLine.LineNumber - 1;
+        }
+
+        private int GetLastVisibleLineIndex()
+        {
+            return _textView.VisualLines[^1].LastDocumentLine.LineNumber - 1;
+        }
+
+        private sealed class InvalidLineRange
+        {
+            public InvalidLineRange(int startLine, int endLine)
+            {
+                StartLine = startLine;
+                EndLine = endLine;
+            }
+
+            public int StartLine { get; private set; }
+
+            public int EndLine { get; private set; }
+
+            public void SetInvalidRange(int startLine, int endLine)
+            {
+                StartLine = Math.Min(StartLine, startLine);
+                EndLine = Math.Max(EndLine, endLine);
+            }
+        }
+    }
 }

tests/AtomUI.Toolkits.GalleryBase.Tests/SourceCode/GalleryCodeViewerRuntimeTests.cs

@@ -8,6 +8,7 @@ using AtomUI.Toolkits.GalleryBase.SourceCode;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
+using Avalonia.Headless;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Layout;
@@ -16,6 +17,7 @@ using Avalonia.Threading;
 using Avalonia.VisualTree;
 using AvaloniaEdit;
 using AvaloniaEdit.Editing;
+using AvaloniaEdit.TextMate;
 using Shouldly;
 using TextMateSharp.Registry;
 using TextMateSharp.Grammars;
@@ -133,6 +135,7 @@ public class GalleryCodeViewerRuntimeTests
             var horizontalScrollBar = editor.GetVisualDescendants()
                                             .OfType<ScrollBar>()
                                             .Single(scrollBar => scrollBar.Orientation == Orientation.Horizontal);
+            var scrollViewer = GetEditorScrollViewer(editor);
 
             // Drive the editor through a range of horizontal scroll offsets, forcing a layout
             // pass at each step. This reproduces the auto-scroll-while-selecting feedback loop:
@@ -140,7 +143,7 @@ public class GalleryCodeViewerRuntimeTests
             // previously re-triggered layout forever and hung the UI thread).
             double MeasureInsetAfterScroll(double offset)
             {
-                editor.ScrollToHorizontalOffset(offset);
+                scrollViewer.Offset = new Vector(offset, scrollViewer.Offset.Y);
                 editor.InvalidateMeasure();
                 editor.InvalidateArrange();
                 Dispatcher.UIThread.RunJobs();
@@ -164,6 +167,192 @@ public class GalleryCodeViewerRuntimeTests
         });
     }
 
+    [Fact]
+    public void GalleryCodeViewer_Selection_Drag_AutoScroll_Does_Not_Hang()
+    {
+        var viewer = new GalleryCodeViewer
+        {
+            CodeText = string.Join(
+                "\n",
+                Enumerable.Range(1, 40).Select(index => $"{index}: {new string('x', 260)}")),
+            Language = "csharp"
+        };
+        var window = new Window
+        {
+            Width   = 640,
+            Height  = 480,
+            Content = viewer
+        };
+
+        try
+        {
+            window.Show();
+            Dispatcher.UIThread.RunJobs();
+            viewer.ApplyTemplate();
+
+            var editor = viewer.GetVisualDescendants()
+                               .OfType<TextEditor>()
+                               .Single();
+            editor.ApplyTemplate();
+            Dispatcher.UIThread.RunJobs();
+
+            var textView = editor.TextArea.TextView;
+            var startPoint = textView.TranslatePoint(new Point(80, 22), window).ShouldNotBeNull();
+            var dragPoint = textView.TranslatePoint(new Point(textView.Bounds.Width + 160, 82), window)
+                                    .ShouldNotBeNull();
+
+            window.MouseMove(startPoint);
+            window.MouseDown(startPoint, MouseButton.Left);
+            window.MouseMove(dragPoint);
+
+            for (var i = 0; i < 8; i++)
+            {
+                Dispatcher.UIThread.RunJobs();
+            }
+
+            window.MouseUp(dragPoint, MouseButton.Left);
+            Dispatcher.UIThread.RunJobs();
+
+            editor.HorizontalOffset.ShouldBeGreaterThan(0);
+            editor.TextArea.Selection.IsEmpty.ShouldBeFalse();
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+        }
+        finally
+        {
+            window.Close();
+            Dispatcher.UIThread.RunJobs();
+            viewer.Dispose();
+        }
+    }
+
+    [Fact]
+    public void GalleryCodeViewer_Keeps_TextMate_When_Click_Does_Not_Start_Selection_Drag()
+    {
+        var viewer = new GalleryCodeViewer
+        {
+            CodeText = string.Join(
+                "\n",
+                Enumerable.Repeat(
+                    "    <atom:TextBlock Foreground=\"{atom:SharedTokenResource ColorTextTertiary}\" Text=\"{Binding Description}\" />",
+                    40)),
+            Language = "axaml"
+        };
+        var window = new Window
+        {
+            Width   = 640,
+            Height  = 480,
+            Content = viewer
+        };
+
+        try
+        {
+            window.Show();
+            Dispatcher.UIThread.RunJobs();
+            viewer.ApplyTemplate();
+
+            var editor = viewer.GetVisualDescendants()
+                               .OfType<TextEditor>()
+                               .Single();
+            editor.ApplyTemplate();
+            Dispatcher.UIThread.RunJobs();
+
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+
+            var startPoint = editor.TextArea.TextView.TranslatePoint(new Point(80, 22), window)
+                                   .ShouldNotBeNull();
+
+            window.MouseMove(startPoint);
+            window.MouseDown(startPoint, MouseButton.Left);
+            Dispatcher.UIThread.RunJobs();
+
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+
+            window.MouseUp(startPoint, MouseButton.Left);
+            Dispatcher.UIThread.RunJobs();
+
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+        }
+        finally
+        {
+            window.Close();
+            Dispatcher.UIThread.RunJobs();
+            viewer.Dispose();
+        }
+    }
+
+    [Fact]
+    public void GalleryCodeViewer_Keeps_TextMate_During_Pointer_Selection_Drag()
+    {
+        var viewer = new GalleryCodeViewer
+        {
+            CodeText = string.Join(
+                "\n",
+                Enumerable.Repeat(
+                    "    <atom:TextBlock Foreground=\"{atom:SharedTokenResource ColorTextTertiary}\" Text=\"{Binding Description}\" />",
+                    40)),
+            Language = "axaml"
+        };
+        var window = new Window
+        {
+            Width   = 640,
+            Height  = 480,
+            Content = viewer
+        };
+
+        try
+        {
+            window.Show();
+            Dispatcher.UIThread.RunJobs();
+            viewer.ApplyTemplate();
+
+            var editor = viewer.GetVisualDescendants()
+                               .OfType<TextEditor>()
+                               .Single();
+            editor.ApplyTemplate();
+            Dispatcher.UIThread.RunJobs();
+
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+
+            var textView = editor.TextArea.TextView;
+            var startPoint = textView.TranslatePoint(new Point(80, 22), window)
+                                     .ShouldNotBeNull();
+            var dragPoint = textView.TranslatePoint(new Point(180, 52), window)
+                                    .ShouldNotBeNull();
+
+            window.MouseMove(startPoint);
+            window.MouseDown(startPoint, MouseButton.Left);
+            window.MouseMove(dragPoint);
+            Dispatcher.UIThread.RunJobs();
+
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+
+            window.MouseUp(dragPoint, MouseButton.Left);
+            Dispatcher.UIThread.RunJobs();
+
+            editor.TextArea.TextView.LineTransformers
+                  .OfType<TextMateColoringTransformer>()
+                  .ShouldNotBeEmpty();
+        }
+        finally
+        {
+            window.Close();
+            Dispatcher.UIThread.RunJobs();
+            viewer.Dispose();
+        }
+    }
+
     [Fact]
     public void GalleryCodeViewer_Uses_Dark_Syntax_Theme_When_AtomUI_Dark_Mode_Is_Enabled()
     {
@@ -607,6 +796,16 @@ public class GalleryCodeViewerRuntimeTests
         return syntaxThemeField.GetValue(viewer).ShouldBeOfType<ThemeName>();
     }
 
+    private static Avalonia.Controls.ScrollViewer GetEditorScrollViewer(TextEditor editor)
+    {
+        var scrollViewerProperty = typeof(TextEditor).GetProperty(
+            "ScrollViewer",
+            BindingFlags.Instance | BindingFlags.NonPublic);
+        scrollViewerProperty.ShouldNotBeNull();
+
+        return scrollViewerProperty.GetValue(editor).ShouldBeOfType<Avalonia.Controls.ScrollViewer>();
+    }
+
     private static string? GetAxamlTagNameColor(GalleryCodeViewer viewer)
     {
         return GetAxamlTokenColor(viewer, "StackPanel");

tests/AtomUI.Toolkits.GalleryBase.Tests/SourceCode/GallerySourceCodeDisplayLayoutTests.cs

@@ -54,6 +54,34 @@ public class GallerySourceCodeDisplayLayoutTests
         viewerMarkup.ShouldContain("x:Key=\"ThemeForegroundColor\"");
     }
 
+    [Fact]
+    public void Code_Viewer_Does_Not_Keep_A_Permanent_LayoutUpdated_Scrollbar_Adjuster()
+    {
+        var viewerSource = File.ReadAllText(GetRepoFile("src/AtomUI.Toolkits.GalleryBase/Controls/GalleryCodeViewer.cs"));
+
+        var requestMethodIndex = viewerSource.IndexOf(
+            "private void RequestHorizontalScrollBarGutterInsetUpdate()",
+            StringComparison.Ordinal);
+        var subscriptionIndex = viewerSource.IndexOf(
+            "_editor.LayoutUpdated += HandleEditorLayoutUpdated",
+            StringComparison.Ordinal);
+        var handlerIndex = viewerSource.IndexOf(
+            "private void HandleEditorLayoutUpdated",
+            StringComparison.Ordinal);
+        var cancelInHandlerIndex = viewerSource.IndexOf(
+            "CancelHorizontalScrollBarGutterInsetUpdate();",
+            handlerIndex,
+            StringComparison.Ordinal);
+        var updateInHandlerIndex = viewerSource.IndexOf(
+            "UpdateHorizontalScrollBarGutterInset();",
+            handlerIndex,
+            StringComparison.Ordinal);
+
+        requestMethodIndex.ShouldBeGreaterThanOrEqualTo(0);
+        subscriptionIndex.ShouldBeGreaterThan(requestMethodIndex);
+        cancelInHandlerIndex.ShouldBeLessThan(updateInHandlerIndex);
+    }
+
     private static string GetRepoFile(string relativePath)
     {
         var directory = new DirectoryInfo(AppContext.BaseDirectory);

tests/AtomUIGallery.Tests/ShowCases/BorderBeamShowCasePageTests.cs

@@ -50,7 +50,7 @@ public class BorderBeamShowCasePageTests
         source.ShouldContain("BorderBeamShowCaseLangResource PageSubtitle");
         source.ShouldContain("BorderBeamShowCaseLangResource PageDescription");
         source.ShouldContain("BorderBeamShowCaseLangResource ComponentCategory");
-        source.ShouldContain("BorderBeamShowCaseLangResource ComponentStatusPreview");
+        source.ShouldContain("BorderBeamShowCaseLangResource ComponentIntroducedVersion");
         source.ShouldContain("BorderBeamShowCaseLangResource ScenarioExamples");
         source.ShouldContain("BorderBeamShowCaseLangResource ScenarioApi");
         source.ShouldContain("BorderBeamShowCaseLangResource ScenarioDesignToken");
@@ -68,6 +68,30 @@ public class BorderBeamShowCasePageTests
         source.ShouldNotContain("<atom:DataGrid");
     }
 
+    [Fact]
+    public void BorderBeam_ShowCase_Header_Centers_Title_Tags_And_Uses_Blue_Introduced_Version_Tag()
+    {
+        var source = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Views/BorderBeamShowCase.axaml");
+        var enSource = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Localization/en_US.cs");
+        var zhCnSource = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Localization/zh_CN.cs");
+        var zhTwSource = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/BorderBeam/Localization/zh_TW.cs");
+        var header = ExtractHeaderTitleMarkup(source);
+
+        header.ShouldContain("<Grid ColumnDefinitions=\"Auto,*\"");
+        header.ShouldContain("<WrapPanel Grid.Column=\"1\"");
+        header.ShouldContain("VerticalAlignment=\"Center\"");
+        header.ShouldContain("Text=\"{gallery:BorderBeamShowCaseLangResource ComponentIntroducedVersion}\"");
+        header.ShouldContain("TagColor=\"blue\"");
+        header.ShouldContain("IsBordered=\"False\"");
+        header.ShouldNotContain("ComponentStatusPreview");
+
+        foreach (var localizationSource in new[] { enSource, zhCnSource, zhTwSource })
+        {
+            localizationSource.ShouldContain("public const string ComponentIntroducedVersion = \"v6.0.5\";");
+            localizationSource.ShouldNotContain("ComponentStatusPreview");
+        }
+    }
+
     [Fact]
     public void BorderBeam_ShowCase_Demos_Match_Ant_Design_Examples()
     {
@@ -189,6 +213,21 @@ public class BorderBeamShowCasePageTests
         return source[itemStart..(itemEnd + itemEndMarker.Length)];
     }
 
+    private static string ExtractHeaderTitleMarkup(string source)
+    {
+        const string headerStartMarker = "Text=\"BorderBeam\"";
+        const string headerEndMarker = "BorderBeamShowCaseLangResource PageSubtitle";
+
+        var titleIndex = source.IndexOf(headerStartMarker, StringComparison.Ordinal);
+        titleIndex.ShouldBeGreaterThanOrEqualTo(0);
+        var headerStart = source.LastIndexOf("<Grid", titleIndex, StringComparison.Ordinal);
+        headerStart.ShouldBeGreaterThanOrEqualTo(0);
+        var headerEnd = source.IndexOf(headerEndMarker, headerStart, StringComparison.Ordinal);
+        headerEnd.ShouldBeGreaterThan(headerStart);
+
+        return source[headerStart..headerEnd];
+    }
+
     private static IEnumerable<GalleryNavigationNode> Walk(IEnumerable<GalleryNavigationNode> nodes)
     {
         foreach (var node in nodes)

tests/AtomUIGallery.Tests/ShowCases/SplashShowCasePageTests.cs

@@ -50,6 +50,7 @@ public class SplashShowCasePageTests
         source.ShouldContain("SplashShowCaseLangResource PageDescription");
         source.ShouldContain("SplashShowCaseLangResource ComponentCategory");
         source.ShouldContain("SplashShowCaseLangResource ComponentStatusPreview");
+        source.ShouldContain("SplashShowCaseLangResource ComponentIntroducedVersion");
         source.ShouldContain("SplashShowCaseLangResource ScenarioExamples");
         source.ShouldContain("SplashShowCaseLangResource ScenarioApi");
         source.ShouldContain("SplashShowCaseLangResource ScenarioDesignToken");
@@ -67,6 +68,29 @@ public class SplashShowCasePageTests
         source.ShouldNotContain("<atom:DataGrid");
     }
 
+    [Fact]
+    public void Splash_ShowCase_Header_Centers_Title_Tags_And_Adds_Blue_Introduced_Version_Tag()
+    {
+        var source = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/Splash/Views/SplashShowCase.axaml");
+        var enSource = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/Splash/Localization/en_US.cs");
+        var zhCnSource = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/Splash/Localization/zh_CN.cs");
+        var zhTwSource = ReadRepoFile("controlgallery/AtomUIGallery/ShowCases/Other/Splash/Localization/zh_TW.cs");
+        var header = ExtractHeaderTitleMarkup(source);
+
+        header.ShouldContain("<Grid ColumnDefinitions=\"Auto,*\"");
+        header.ShouldContain("<WrapPanel Grid.Column=\"1\"");
+        header.ShouldContain("VerticalAlignment=\"Center\"");
+        header.ShouldContain("Text=\"{gallery:SplashShowCaseLangResource ComponentStatusPreview}\"");
+        header.ShouldContain("Text=\"{gallery:SplashShowCaseLangResource ComponentIntroducedVersion}\"");
+        header.ShouldContain("TagColor=\"blue\"");
+        header.ShouldContain("IsBordered=\"False\"");
+
+        foreach (var localizationSource in new[] { enSource, zhCnSource, zhTwSource })
+        {
+            localizationSource.ShouldContain("public const string ComponentIntroducedVersion = \"v6.0.7\";");
+        }
+    }
+
     [Fact]
     public void Splash_ShowCase_Demos_Cover_Visual_States_Without_Showing_Window()
     {
@@ -257,6 +281,21 @@ public class SplashShowCasePageTests
         return source[itemStart..(itemEnd + itemEndMarker.Length)];
     }
 
+    private static string ExtractHeaderTitleMarkup(string source)
+    {
+        const string headerStartMarker = "Text=\"Splash\"";
+        const string headerEndMarker = "SplashShowCaseLangResource PageSubtitle";
+
+        var titleIndex = source.IndexOf(headerStartMarker, StringComparison.Ordinal);
+        titleIndex.ShouldBeGreaterThanOrEqualTo(0);
+        var headerStart = source.LastIndexOf("<Grid", titleIndex, StringComparison.Ordinal);
+        headerStart.ShouldBeGreaterThanOrEqualTo(0);
+        var headerEnd = source.IndexOf(headerEndMarker, headerStart, StringComparison.Ordinal);
+        headerEnd.ShouldBeGreaterThan(headerStart);
+
+        return source[headerStart..headerEnd];
+    }
+
     private static IEnumerable<GalleryNavigationNode> Walk(IEnumerable<GalleryNavigationNode> nodes)
     {
         foreach (var node in nodes)