diff --git a/windows/src/engine/keyman32/KEYMAN32.DEF b/windows/src/engine/keyman32/KEYMAN32.DEF
index 4403ae0812..8ff4978154 100644
--- a/windows/src/engine/keyman32/KEYMAN32.DEF
+++ b/windows/src/engine/keyman32/KEYMAN32.DEF
@@ -23,13 +23,14 @@ EXPORTS
       GetKeyboardPreservedKeys
 
 			GetActiveKeymanID
-			Keyman_RegisterControllerThread
-			Keyman_UnregisterControllerThread
+			Keyman_RegisterControllerWindow
+			Keyman_UnregisterControllerWindow
       Keyman_RegisterMasterController
       Keyman_UnregisterMasterController
 			Keyman_RestartEngine
 
       Keyman_SendMasterController
+			Keyman_PostControllers
       Keyman_PostMasterController
 
       Keyman_StartExit
@@ -40,3 +41,6 @@ EXPORTS
       Keyman_UpdateTouchPanelVisibility
 
       Keyman_Diagnostic
+
+			Keyman_RegisterControllerThread
+			Keyman_UnregisterControllerThread
diff --git a/windows/src/engine/keyman32/k32_globals.cpp b/windows/src/engine/keyman32/k32_globals.cpp
index 2e10f7d3c6..f4a32165f7 100644
--- a/windows/src/engine/keyman32/k32_globals.cpp
+++ b/windows/src/engine/keyman32/k32_globals.cpp
@@ -551,6 +551,12 @@ LRESULT Globals::SendMasterController(UINT msg, WPARAM wParam, LPARAM lParam)
   return dwResult;
 }
 
+extern "C" void  _declspec(dllexport) WINAPI Keyman_PostControllers(UINT msg, WPARAM wParam, LPARAM lParam)
+{
+  // no-op (removed as part of #5060)
+  return 0;
+}
+
 extern "C" void  _declspec(dllexport) WINAPI Keyman_PostMasterController(UINT msg, WPARAM wParam, LPARAM lParam)
 {
   Globals::PostMasterController(msg, wParam, lParam);
@@ -561,6 +567,12 @@ extern "C" LRESULT  _declspec(dllexport) WINAPI Keyman_SendMasterController(UINT
   return Globals::SendMasterController(msg, wParam, lParam);
 }
 
+extern "C" BOOL  _declspec(dllexport) WINAPI Keyman_RegisterControllerWindow(HWND hwnd)
+{
+  // no-op (removed as part of #5060)
+  return TRUE;
+}
+
 extern "C" BOOL  _declspec(dllexport) WINAPI Keyman_RegisterControllerThread(DWORD tid)
 {
   if(!Globals::Lock())
@@ -599,6 +611,12 @@ extern "C" BOOL  _declspec(dllexport) WINAPI Keyman_RegisterMasterController(HWN
   return TRUE;
 }
 
+extern "C" BOOL  _declspec(dllexport) WINAPI Keyman_UnregisterControllerWindow(HWND hwnd)
+{
+  // no-op (removed as part of #5060)
+  return TRUE;
+}
+
 extern "C" BOOL _declspec(dllexport) WINAPI Keyman_UnregisterControllerThread(DWORD tid)
 {
   if(!Globals::Lock()) return FALSE;
diff --git a/windows/src/engine/kmcomapi/com/system/keymancontrol.pas b/windows/src/engine/kmcomapi/com/system/keymancontrol.pas
index cd192c2453..f0bb264398 100644
--- a/windows/src/engine/kmcomapi/com/system/keymancontrol.pas
+++ b/windows/src/engine/kmcomapi/com/system/keymancontrol.pas
@@ -143,10 +143,8 @@ type
     procedure StartKeyman32Engine; safecall;    // 32 bit only
     procedure StopKeyman32Engine; safecall;    // 32 bit only
     procedure ResetKeyman32Engine; safecall;    // 32 bit only
-    procedure RegisterMasterController(Value: LongWord); safecall;     // 32 bit only
-    procedure UnregisterMasterController(Value: LongWord); safecall;    // 32 bit only
-    procedure RegisterControllerThread(Value: LongWord); safecall;     // 32 bit only
-    procedure UnregisterControllerThread(Value: LongWord); safecall;    // 32 bit only
+    procedure RegisterControllerWindow(Value: LongWord); safecall;     // deprecated in #5060
+    procedure UnregisterControllerWindow(Value: LongWord); safecall;    // deprecated in #5060
     procedure DisableUserInterface; safecall;
     procedure EnableUserInterface; safecall;
     procedure UpdateTouchPanelVisibility(Value: Boolean); safecall;
@@ -155,6 +153,12 @@ type
 
     function LastRefreshToken: IntPtr; safecall;
 
+    // #5060:
+    procedure RegisterMasterController(Value: LongWord); safecall;     // 32 bit only
+    procedure UnregisterMasterController(Value: LongWord); safecall;    // 32 bit only
+    procedure RegisterControllerThread(Value: LongWord); safecall;     // 32 bit only
+    procedure UnregisterControllerThread(Value: LongWord); safecall;    // 32 bit only
+
     { IIntKeymanControl }
     procedure AutoApplyKeyman;
     procedure ApplyKeyman;
@@ -533,6 +537,11 @@ begin
 {$ENDIF}
 end;
 
+procedure TKeymanControl.RegisterControllerWindow(Value: LongWord);
+begin
+  // no-op (removed as part of #5060)
+end;
+
 procedure TKeymanControl.RegisterMasterController(Value: LongWord);
 begin
 {$IFDEF WIN64}
@@ -577,6 +586,11 @@ begin
 {$ENDIF}
 end;
 
+procedure TKeymanControl.UnregisterControllerWindow(Value: LongWord);
+begin
+  // no-op (removed as part of #5060)
+end;
+
 procedure TKeymanControl.UnregisterMasterController(Value: LongWord);
 begin
 {$IFDEF WIN64}
diff --git a/windows/src/global/delphi/general/KeymanEngineControl.pas b/windows/src/global/delphi/general/KeymanEngineControl.pas
index dd3b6b1ddd..5afd6f9013 100644
--- a/windows/src/global/delphi/general/KeymanEngineControl.pas
+++ b/windows/src/global/delphi/general/KeymanEngineControl.pas
@@ -27,10 +27,8 @@ type
     procedure StartKeyman32Engine; safecall;   // I5133
     procedure StopKeyman32Engine; safecall;   // I5133
     procedure ResetKeyman32Engine; safecall;   // I5133
-    procedure RegisterMasterController(Value: LongWord); safecall;
-    procedure UnregisterMasterController(Value: LongWord); safecall;
-    procedure RegisterControllerThread(Value: LongWord); safecall;
-    procedure UnregisterControllerThread(Value: LongWord); safecall;
+    procedure RegisterControllerWindow(Value: LongWord); safecall; // deprecated in #5060; remains for interface stability
+    procedure UnregisterControllerWindow(Value: LongWord); safecall; // deprecated in #5060; remains for interface stability
     procedure DisableUserInterface; safecall;
     procedure EnableUserInterface; safecall;
     procedure UpdateTouchPanelVisibility(Value: Boolean); safecall;
@@ -38,6 +36,13 @@ type
     procedure DiagnosticTestException; safecall;
 
     function LastRefreshToken: IntPtr; safecall;
+
+    // New in #5060:
+
+    procedure RegisterMasterController(Value: LongWord); safecall;
+    procedure UnregisterMasterController(Value: LongWord); safecall;
+    procedure RegisterControllerThread(Value: LongWord); safecall;
+    procedure UnregisterControllerThread(Value: LongWord); safecall;
   end;
 
 implementation