From e04ef76053ffdee2182223b393d1d0c69ec1a26d Mon Sep 17 00:00:00 2001
From: calisto-le <46937480+calisto-le@users.noreply.github.com>
Date: Fri, 15 May 2026 16:56:20 +0200
Subject: [PATCH 1/2] Fix TextServicesManager scan code forwarding for TSF

Fixes #11635
---
 .../System/Windows/Input/TextServicesManager.cs                 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs b/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs
index bed4fa4aa7a..f01a85a3e91 100644
--- a/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs
+++ b/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs
@@ -231,7 +231,7 @@ private bool TextServicesKeystroke(TextServicesContext context, KeyEventArgs key
                     break;
                 default:
                     wParam = KeyInterop.VirtualKeyFromKey(keyArgs.RealKey);
-                    scancode = 0; 
+                    scancode = keyArgs.ScanCode;
                     break;
             }
 

From bbb1513bd7d7f4a721f1bf617464ca0d50991027 Mon Sep 17 00:00:00 2001
From: calisto-le <46937480+calisto-le@users.noreply.github.com>
Date: Sat, 16 May 2026 12:39:39 +0200
Subject: [PATCH 2/2] Preserve extended key flag in lParam

---
 .../System/Windows/Input/TextServicesManager.cs            | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs b/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs
index f01a85a3e91..f4b09ed84e9 100644
--- a/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs
+++ b/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TextServicesManager.cs
@@ -235,7 +235,12 @@ private bool TextServicesKeystroke(TextServicesContext context, KeyEventArgs key
                     break;
             }
 
-            lParam = (int)(((uint)scancode << 16) | 1);
+            lParam = (int)((((uint)scancode & 0xFF) << 16) | 1);
+
+            if (keyArgs.IsExtendedKey)
+            {
+                lParam |= 1 << 24;
+            }
 
             if (keyArgs.RoutedEvent == Keyboard.PreviewKeyDownEvent/*keyArgs.IsDown*/)
             {