Major production merge: GTK support, context menus, and dispatcher fixes

Core Infrastructure:
- Add Dispatching folder with LinuxDispatcher, LinuxDispatcherProvider, LinuxDispatcherTimer
- Add Native folder with P/Invoke wrappers (GTK, GLib, GDK, Cairo, WebKit)
- Add GTK host window system with GtkHostWindow and GtkSkiaSurfaceWidget
- Update LinuxApplication with GTK mode, theme handling, and icon support
- Fix duplicate LinuxDispatcher in LinuxMauiContext

Handlers:
- Add GtkWebViewManager and GtkWebViewPlatformView for GTK WebView
- Add FlexLayoutHandler and GestureManager
- Update multiple handlers with ToViewHandler fix and missing mappers
- Add MauiHandlerExtensions with ToViewHandler extension method

Views:
- Add SkiaContextMenu with hover, keyboard, and dark theme support
- Add LinuxDialogService with context menu management
- Add SkiaFlexLayout for flex container support
- Update SkiaShell with RefreshTheme, MauiShell, ContentRenderer
- Update SkiaWebView with SetMainWindow, ProcessGtkEvents
- Update SkiaImage with LoadFromBitmap method

Services:
- Add AppInfoService, ConnectivityService, DeviceDisplayService, DeviceInfoService
- Add GtkHostService, GtkContextMenuService, MauiIconGenerator

Window:
- Add CursorType enum and GtkHostWindow
- Update X11Window with SetIcon, SetCursor methods

Build: SUCCESS (0 errors)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Hosting/MauiHandlerExtensions.cs

@@ -0,0 +1,123 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Platform.Linux.Handlers;
+
+namespace Microsoft.Maui.Platform.Linux.Hosting;
+
+/// <summary>
+/// Extension methods for creating MAUI handlers on Linux.
+/// Maps MAUI types to Linux-specific handlers with fallback to MAUI defaults.
+/// </summary>
+public static class MauiHandlerExtensions
+{
+    private static readonly Dictionary<Type, Func<IElementHandler>> LinuxHandlerMap = new Dictionary<Type, Func<IElementHandler>>
+    {
+        [typeof(Button)] = () => new TextButtonHandler(),
+        [typeof(Label)] = () => new LabelHandler(),
+        [typeof(Entry)] = () => new EntryHandler(),
+        [typeof(Editor)] = () => new EditorHandler(),
+        [typeof(CheckBox)] = () => new CheckBoxHandler(),
+        [typeof(Switch)] = () => new SwitchHandler(),
+        [typeof(Slider)] = () => new SliderHandler(),
+        [typeof(Stepper)] = () => new StepperHandler(),
+        [typeof(ProgressBar)] = () => new ProgressBarHandler(),
+        [typeof(ActivityIndicator)] = () => new ActivityIndicatorHandler(),
+        [typeof(Picker)] = () => new PickerHandler(),
+        [typeof(DatePicker)] = () => new DatePickerHandler(),
+        [typeof(TimePicker)] = () => new TimePickerHandler(),
+        [typeof(SearchBar)] = () => new SearchBarHandler(),
+        [typeof(RadioButton)] = () => new RadioButtonHandler(),
+        [typeof(WebView)] = () => new WebViewHandler(),
+        [typeof(Image)] = () => new ImageHandler(),
+        [typeof(ImageButton)] = () => new ImageButtonHandler(),
+        [typeof(BoxView)] = () => new BoxViewHandler(),
+        [typeof(Frame)] = () => new FrameHandler(),
+        [typeof(Border)] = () => new BorderHandler(),
+        [typeof(ContentView)] = () => new BorderHandler(),
+        [typeof(ScrollView)] = () => new ScrollViewHandler(),
+        [typeof(Grid)] = () => new GridHandler(),
+        [typeof(StackLayout)] = () => new StackLayoutHandler(),
+        [typeof(VerticalStackLayout)] = () => new StackLayoutHandler(),
+        [typeof(HorizontalStackLayout)] = () => new StackLayoutHandler(),
+        [typeof(AbsoluteLayout)] = () => new LayoutHandler(),
+        [typeof(FlexLayout)] = () => new FlexLayoutHandler(),
+        [typeof(CollectionView)] = () => new CollectionViewHandler(),
+        [typeof(ListView)] = () => new CollectionViewHandler(),
+        [typeof(Page)] = () => new PageHandler(),
+        [typeof(ContentPage)] = () => new ContentPageHandler(),
+        [typeof(NavigationPage)] = () => new NavigationPageHandler(),
+        [typeof(Shell)] = () => new ShellHandler(),
+        [typeof(FlyoutPage)] = () => new FlyoutPageHandler(),
+        [typeof(TabbedPage)] = () => new TabbedPageHandler(),
+        [typeof(Application)] = () => new ApplicationHandler(),
+        [typeof(Microsoft.Maui.Controls.Window)] = () => new WindowHandler(),
+        [typeof(GraphicsView)] = () => new GraphicsViewHandler()
+    };
+
+    /// <summary>
+    /// Creates an element handler for the given element.
+    /// </summary>
+    public static IElementHandler ToHandler(this IElement element, IMauiContext mauiContext)
+    {
+        return CreateHandler(element, mauiContext)!;
+    }
+
+    /// <summary>
+    /// Creates a view handler for the given view.
+    /// </summary>
+    public static IViewHandler? ToViewHandler(this IView view, IMauiContext mauiContext)
+    {
+        var handler = CreateHandler((IElement)view, mauiContext);
+        return handler as IViewHandler;
+    }
+
+    private static IElementHandler? CreateHandler(IElement element, IMauiContext mauiContext)
+    {
+        Type type = element.GetType();
+        IElementHandler? handler = null;
+
+        // First, try exact type match
+        if (LinuxHandlerMap.TryGetValue(type, out Func<IElementHandler>? factory))
+        {
+            handler = factory();
+            Console.WriteLine($"[ToHandler] Using Linux handler for {type.Name}: {handler.GetType().Name}");
+        }
+        else
+        {
+            // Try to find a base type match
+            Type? bestMatch = null;
+            Func<IElementHandler>? bestFactory = null;
+
+            foreach (var kvp in LinuxHandlerMap)
+            {
+                if (kvp.Key.IsAssignableFrom(type) && (bestMatch == null || bestMatch.IsAssignableFrom(kvp.Key)))
+                {
+                    bestMatch = kvp.Key;
+                    bestFactory = kvp.Value;
+                }
+            }
+
+            if (bestFactory != null)
+            {
+                handler = bestFactory();
+                Console.WriteLine($"[ToHandler] Using Linux handler (via base {bestMatch!.Name}) for {type.Name}: {handler.GetType().Name}");
+            }
+        }
+
+        // Fall back to MAUI's default handler
+        if (handler == null)
+        {
+            handler = mauiContext.Handlers.GetHandler(type);
+            Console.WriteLine($"[ToHandler] Using MAUI handler for {type.Name}: {handler?.GetType().Name ?? "null"}");
+        }
+
+        if (handler != null)
+        {
+            handler.SetMauiContext(mauiContext);
+            handler.SetVirtualView(element);
+        }
+
+        return handler;
+    }
+}