fix immediate rendering hit testing for AdornerLayer

src/Avalonia.Controls/Primitives/AdornerLayer.cs

@@ -138,10 +138,7 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
-        public bool HitTest(Point point)
-        {
-            return Children.Any(ctrl => ctrl.TransformedBounds?.Contains(point) == true);
-        }
+        public bool HitTest(Point point) => Children.HitTestCustom(point);
 
         private class AdornedElementInfo
         {

src/Avalonia.Visuals/Rendering/ICustomSimpleHitTest.cs

@@ -1,3 +1,7 @@
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia.VisualTree;
+
 namespace Avalonia.Rendering
 {
     /// <summary>
@@ -9,4 +13,13 @@ namespace Avalonia.Rendering
     {
         bool HitTest(Point point);
     }
+
+    public static class CustomSimpleHitTestExtensions
+    {
+        public static bool HitTestCustom(this IVisual visual, Point point)
+            => (visual as ICustomSimpleHitTest)?.HitTest(point) ?? visual.TransformedBounds?.Contains(point) == true;
+
+        public static bool HitTestCustom(this IEnumerable<IVisual> children, Point point)
+            => children.Any(ctrl => ctrl.HitTestCustom(point));
+    }
 }