fix: Identify the root (desktop) element by UIA class name, not runti…

…me ID (#1048)

On Windows 11 24H2 (GE), the runtime ID of the desktop element changed from
`[2A,10010]` to `[2A,1000C]`, causing live inspect in Accessibility
Insights for Windows to break. This commit switches to identifying the
desktop element by its UIA class name, which has been stable across all
supported Windows versions.

Addresses microsoft/accessibility-insights-windows#1837.

src/Core/Misc/ExtensionMethods.cs

@@ -27,13 +27,14 @@ namespace Axe.Windows.Core.Misc
     public static class ExtensionMethods
     {
         /// <summary>
-        /// DesktopElement runtime Id.
+        /// UIA class name of the root (desktop) element
         /// </summary>
-        const string DesktopElementRuntimeId = "[2A,10010]";
+        const string DesktopElementClassName = "#32769";
+
         /// <summary>
         /// WCOS runtime ID
         /// </summary>
-        const string WCOSElementRuntimeId = "[0,0]";
+        const string WCOSDesktopElementRuntimeId = "[0,0]";
 
         /// <summary>
         /// Get A11yElementData object out of A11yElement
@@ -638,19 +639,12 @@ public static bool IsOffScreen(this A11yElement e)
         /// <returns></returns>
         public static bool IsRootElement(this IA11yElement e)
         {
-            // on Desktop, RuntimeId is available with specific ID.
-            // however on WCOS, the desktop equivalent process is PID 0 and runtime ID is 0,0
-            return e != null && (e.RuntimeId == DesktopElementRuntimeId || (e.ProcessId == 0 && e.RuntimeId == WCOSElementRuntimeId));
-        }
-
-        /// <summary>
-        /// Check whether string is matched with DesktopElment runtime Id.
-        /// </summary>
-        /// <param name="str"></param>
-        /// <returns></returns>
-        public static bool IsDesktopElementRuntimeId(string str)
-        {
-            return DesktopElementRuntimeId == str;
+            // On Windows, check for the desktop (root) element by class name.
+            // On WCOS, check for the desktop by process and runtime IDs.
+            return e != null && (
+                e.ClassName == DesktopElementClassName
+                || (e.ProcessId == 0 && e.RuntimeId == WCOSDesktopElementRuntimeId)
+            );
         }
 
         /// <summary>

src/RulesTest/PropertyConditions/BoolPropertiesTests.cs

@@ -130,7 +130,7 @@ public void TestIsDesktopTrue()
         {
             using (var e = new MockA11yElement())
             {
-                var property = new A11yProperty(PropertyType.UIA_RuntimeIdPropertyId, new int[] { 0x2A, 0x10010 });
+                var property = new A11yProperty(PropertyType.UIA_ClassNamePropertyId, "#32769");
                 e.Properties.Add(property.Id, property);
                 Assert.IsTrue(IsDesktop.Matches(e));
             } // using
@@ -159,7 +159,7 @@ public void TestIsNotDesktopFalse()
         {
             using (var e = new MockA11yElement())
             {
-                var property = new A11yProperty(PropertyType.UIA_RuntimeIdPropertyId, new int[] { 0x2A, 0x10010 });
+                var property = new A11yProperty(PropertyType.UIA_ClassNamePropertyId, "#32769");
                 e.Properties.Add(property.Id, property);
                 Assert.IsFalse(IsNotDesktop.Matches(e));
             } // using