feat: Initial page focus on WASM using browser keyboard navigation

src/Uno.UI/UI/Xaml/Input/FocusManager.wasm.cs

@@ -124,6 +124,26 @@ public static void ReceiveFocusNative(int handle)
 			}
 			else if (focused != null)
 			{
+				// Special handling for RootVisual - which is not focusable on managed side
+				// but is focusable on native side. The purpose of this trick is to allow
+				// us to recognize, that the page was focused by tabbing from the address bar
+				// and focusing the first focusable element on the page instead.
+				if (focused is RootVisual rootVisual)
+				{					
+					var firstFocusable = FocusManager.FindFirstFocusableElement(rootVisual);
+					if (firstFocusable is FrameworkElement frameworkElement)
+					{
+						if (_log.Value.IsEnabled(LogLevel.Debug))
+						{
+							_log.Value.LogDebug(
+								$"Root visual focused - caused by browser keyboard navigation to the page, " +
+								$"moving focus to actual first focusable element - {frameworkElement?.ToString() ?? "[null]"}.");
+						}
+						frameworkElement.Focus(FocusState.Keyboard);
+					}
+					return;
+				}
+
 				ProcessElementFocused(focused);
 			}
 			else

src/Uno.UI/UI/Xaml/Internal/RootVisual.cs

@@ -27,18 +27,22 @@ internal partial class RootVisual : Panel
 		public RootVisual(CoreServices coreServices)
 		{
 			_coreServices = coreServices ?? throw new System.ArgumentNullException(nameof(coreServices));
-			//Uno specific - flag as VisualTreeRoot for interop with existing logic
+            //Uno specific - flag as VisualTreeRoot for interop with existing logic
 			IsVisualTreeRoot = true;
+#if __WASM__
+			//Uno WASM specific - set tabindex to 0 so the RootVisual is "native focusable"
+			SetAttribute("tabindex", "0");
+#endif
 
 			PointerPressed += RootVisual_PointerPressed;
 			PointerReleased += RootVisual_PointerReleased;
 			PointerCanceled += RootVisual_PointerCanceled;
 		}
 
-		/// <summary>
-		/// Gets or sets the Visual Tree.
-		/// </summary>
-		internal VisualTree? AssociatedVisualTree { get; set; }
+        /// <summary>
+        /// Gets or sets the Visual Tree.
+        /// </summary>
+        internal VisualTree? AssociatedVisualTree { get; set; }
 
 		internal PopupRoot? AssociatedPopupRoot =>
 			AssociatedVisualTree?.PopupRoot ?? this.GetContext().MainPopupRoot;