Use TryUnwrapManagedObject in drag'n'drop

src/Avalonia.MicroCom/MicroComProxyBase.cs

@@ -61,22 +61,6 @@ namespace Avalonia.MicroCom
             throw new COMException("QueryInterface failed", rv);
         }
 
-        public bool TryQueryInterface<T>(out T result) where T : IUnknown
-        {
-            var guid = MicroComRuntime.GetGuidFor(typeof(T));
-            var rv = QueryInterface(guid, out var ppv);
-            if (rv == 0)
-            {
-                result = (T)MicroComRuntime.CreateProxyFor(typeof(T), ppv, true);
-                return true;
-            }
-            else
-            {
-                result = default;
-                return false;
-            }
-        }
-
         public bool IsDisposed => _nativePointer == IntPtr.Zero;
 
         protected virtual void Dispose(bool disposing)

src/Windows/Avalonia.Win32/DataObject.cs

@@ -31,25 +31,16 @@ namespace Avalonia.Win32
                 return disposableDataObject;
             }
 
-            // If DataObject was created on the our side (drag'n'drop initiated by Avalonia),
-            // then pDataObj will implement IAvnDataObject interface as well. So we can safely case it back to DataObject.
-            if (((MicroComProxyBase)pDataObj).TryQueryInterface<Win32Com.IAvnDataObject>(out var avnInterface))
+            var dataObject = MicroComRuntime.TryUnwrapManagedObject(pDataObj) as DataObject;
+            if (dataObject is not null)
             {
-                using (avnInterface)
-                {
-                    var ppv = MicroComRuntime.GetNativeIntPtr(avnInterface);
-                    return MicroComRuntime.GetObjectFromCcw(ppv) as DataObject;
-                }
-            }
-            // Otherwise wrap pDataObj into OleDataObject.
-            else
-            {
-                return new OleDataObject(pDataObj);
+                return dataObject;
             }
+            return new OleDataObject(pDataObj);
         }
     }
 
-    internal class DataObject : CallbackBase, IDisposableDataObject, Win32Com.IAvnDataObject
+    internal class DataObject : CallbackBase, IDisposableDataObject, Win32Com.IDataObject
     {
         // Compatibility with WinForms + WPF...
         internal static readonly byte[] SerializedObjectGUID = new Guid("FD9EA796-3B13-4370-A679-56106BB288FB").ToByteArray();

src/Windows/Avalonia.Win32/Win32Com/win32.idl

@@ -267,11 +267,6 @@ interface IDataObject : IUnknown
         [out] void** ppenumAdvise);
 }
 
-[uuid(3d74307e-12be-460a-b098-4dd320eec7d5)]
-interface IAvnDataObject : IDataObject
-{
-}
-
 [
     local,
     object,