Merge commit 'd5921485825af547a2f0e042773eab05048465fd'

Author: Mirroring

src/System.Windows.Forms/src/System/Windows/Forms/ActiveX/AxHost.cs

@@ -3234,13 +3234,14 @@ protected override unsafe void WndProc(ref Message m)
 
     private unsafe void DetachAndForward(ref Message m)
     {
+        HWND handle = GetHandleNoCreate();
         DetachWindow();
-        if (IsHandleCreated)
+        if (!handle.IsNull)
         {
-            void* wndProc = (void*)PInvoke.GetWindowLong(this, WINDOW_LONG_PTR_INDEX.GWL_WNDPROC);
+            void* wndProc = (void*)PInvoke.GetWindowLong(handle, WINDOW_LONG_PTR_INDEX.GWL_WNDPROC);
             m.ResultInternal = PInvoke.CallWindowProc(
                 (delegate* unmanaged[Stdcall]<HWND, uint, WPARAM, LPARAM, LRESULT>)wndProc,
-                HWND,
+                handle,
                 (uint)m.Msg,
                 m.WParamInternal,
                 m.LParamInternal);