diff --git a/dll/ime/msctfime/bridge.cpp b/dll/ime/msctfime/bridge.cpp
index e7801024cf9..ed74a566328 100644
--- a/dll/ime/msctfime/bridge.cpp
+++ b/dll/ime/msctfime/bridge.cpp
@@ -178,6 +178,7 @@ HRESULT CicBridge::DestroyInputContext(TLS *pTLS, HIMC hIMC)
     return hr;
 }
 
+/// @implemented
 ITfContext *
 CicBridge::GetInputContext(CicIMCCLock<CTFIMECONTEXT>& imeContext)
 {
@@ -187,14 +188,22 @@ CicBridge::GetInputContext(CicIMCCLock<CTFIMECONTEXT>& imeContext)
     return pCicIC->m_pContext;
 }
 
-/// @unimplemented
+/// @implemented
 HRESULT CicBridge::OnSetOpenStatus(
     TLS *pTLS,
     ITfThreadMgr_P *pThreadMgr,
     CicIMCLock& imcLock,
     CicInputContext *pCicIC)
 {
-    return E_NOTIMPL;
+    if (!imcLock.get().fOpen && imcLock.ValidCompositionString())
+        pCicIC->EscbCompComplete(imcLock);
+
+    pTLS->m_bNowOpening = TRUE;
+    HRESULT hr = SetCompartmentDWORD(m_cliendId, pThreadMgr,
+                                     GUID_COMPARTMENT_KEYBOARD_OPENCLOSE,
+                                     imcLock.get().fOpen, FALSE);
+    pTLS->m_bNowOpening = FALSE;
+    return hr;
 }
 
 /// Selects the IME context.
diff --git a/dll/ime/msctfime/functions.cpp b/dll/ime/msctfime/functions.cpp
index 2852aece1cd..e3133022023 100644
--- a/dll/ime/msctfime/functions.cpp
+++ b/dll/ime/msctfime/functions.cpp
@@ -1,7 +1,7 @@
 /*
  * PROJECT:     ReactOS msctfime.ime
  * LICENSE:     LGPL-2.1-or-later (https://spdx.org/licenses/LGPL-2.1-or-later)
- * PURPOSE:     The functions of msctfime.ime
+ * PURPOSE:     The functionalities of msctfime.ime
  * COPYRIGHT:   Copyright 2024 Katayama Hirofumi MZ <katayama.hirofumi.mz@gmail.com>
  */
 
diff --git a/dll/ime/msctfime/functions.h b/dll/ime/msctfime/functions.h
index 6938162a6e5..d0b7d8c2ebe 100644
--- a/dll/ime/msctfime/functions.h
+++ b/dll/ime/msctfime/functions.h
@@ -1,7 +1,7 @@
 /*
  * PROJECT:     ReactOS msctfime.ime
  * LICENSE:     LGPL-2.1-or-later (https://spdx.org/licenses/LGPL-2.1-or-later)
- * PURPOSE:     The functions of msctfime.ime
+ * PURPOSE:     The functionalities of msctfime.ime
  * COPYRIGHT:   Copyright 2024 Katayama Hirofumi MZ <katayama.hirofumi.mz@gmail.com>
  */
 
diff --git a/dll/ime/msctfime/inputcontext.cpp b/dll/ime/msctfime/inputcontext.cpp
index 81344d26545..7362040c8fb 100644
--- a/dll/ime/msctfime/inputcontext.cpp
+++ b/dll/ime/msctfime/inputcontext.cpp
@@ -260,6 +260,12 @@ HRESULT CicInputContext::EscbClearDocFeedBuffer(CicIMCLock& imcLock, BOOL bFlag)
     return E_NOTIMPL;
 }
 
+/// @unimplemented
+HRESULT CicInputContext::EscbCompComplete(CicIMCLock& imcLock)
+{
+    return E_NOTIMPL;
+}
+
 /// @unimplemented
 HRESULT
 CicInputContext::SetupReconvertString(
diff --git a/dll/ime/msctfime/inputcontext.h b/dll/ime/msctfime/inputcontext.h
index b567304b779..185d9b8161b 100644
--- a/dll/ime/msctfime/inputcontext.h
+++ b/dll/ime/msctfime/inputcontext.h
@@ -91,6 +91,7 @@ public:
 
     HRESULT SetupDocFeedString(CicIMCLock& imcLock, UINT uCodePage);
     HRESULT EscbClearDocFeedBuffer(CicIMCLock& imcLock, BOOL bFlag);
+    HRESULT EscbCompComplete(CicIMCLock& imcLock);
     HRESULT SetupReconvertString(
         CicIMCLock& imcLock,
         ITfThreadMgr_P *pThreadMgr,
diff --git a/dll/ime/msctfime/tls.h b/dll/ime/msctfime/tls.h
index 28f6d427177..ae1a6000e9c 100644
--- a/dll/ime/msctfime/tls.h
+++ b/dll/ime/msctfime/tls.h
@@ -25,7 +25,7 @@ public:
     DWORD m_dwFlags2;
     DWORD m_dwUnknown2;
     BOOL m_bDestroyed;
-    DWORD m_dwNowOpening;
+    BOOL m_bNowOpening;
     DWORD m_NonEAComposition;
     DWORD m_cWnds;
 
diff --git a/dll/ime/msctfime/ui.cpp b/dll/ime/msctfime/ui.cpp
index 2fec663f97f..fb8ae4105a9 100644
--- a/dll/ime/msctfime/ui.cpp
+++ b/dll/ime/msctfime/ui.cpp
@@ -444,15 +444,14 @@ UI::~UI()
     delete m_pComp;
 }
 
-/// @unimplemented
+/// @implemented
 HRESULT UI::_Create()
 {
     m_pComp = new(cicNoThrow) UIComposition();
     if (!m_pComp)
         return E_OUTOFMEMORY;
 
-    SetWindowLongPtrW(m_hWnd, UIGWLP_UI, (LONG_PTR)this);
-    //FIXME
+    ::SetWindowLongPtrW(m_hWnd, UIGWLP_UI, (LONG_PTR)this);
     return S_OK;
 }
 
@@ -460,13 +459,13 @@ HRESULT UI::_Create()
 void UI::_Destroy()
 {
     m_pComp->OnDestroy();
-    SetWindowLongPtrW(m_hWnd, UIGWLP_UI, 0);
+    ::SetWindowLongPtrW(m_hWnd, UIGWLP_UI, 0);
 }
 
 /// @implemented
 void UI::OnCreate(HWND hWnd)
 {
-    UI *pUI = (UI*)GetWindowLongPtrW(hWnd, UIGWLP_UI);
+    UI *pUI = (UI*)::GetWindowLongPtrW(hWnd, UIGWLP_UI);
     if (pUI)
         return;
     pUI = new(cicNoThrow) UI(hWnd);
@@ -477,7 +476,7 @@ void UI::OnCreate(HWND hWnd)
 /// @implemented
 void UI::OnDestroy(HWND hWnd)
 {
-    UI *pUI = (UI*)GetWindowLongPtrW(hWnd, UIGWLP_UI);
+    UI *pUI = (UI*)::GetWindowLongPtrW(hWnd, UIGWLP_UI);
     if (!pUI)
         return;
 
@@ -656,7 +655,7 @@ UIWndProc(
 
 /***********************************************************************/
 
-/// @unimplemented
+/// @implemented
 BOOL RegisterImeClass(VOID)
 {
     WNDCLASSEXW wcx;