diff --git a/dlls/imm32/imm.c b/dlls/imm32/imm.c
index c5b5895bec8..89541612ea2 100644
--- a/dlls/imm32/imm.c
+++ b/dlls/imm32/imm.c
@@ -100,14 +100,6 @@ typedef struct _tagTRANSMSG {
     LPARAM lParam;
 } TRANSMSG, *LPTRANSMSG;
 
-typedef struct _tagIMMThreadData {
-    struct list entry;
-    DWORD threadID;
-    HWND hwndDefault;
-    BOOL disableIME;
-    DWORD windowRefs;
-} IMMThreadData;
-
 struct coinit_spy
 {
     IInitializeSpy IInitializeSpy_iface;
@@ -123,20 +115,9 @@ struct coinit_spy
 };
 
 static struct list ImmHklList = LIST_INIT(ImmHklList);
-static struct list ImmThreadDataList = LIST_INIT(ImmThreadDataList);
 
 static const WCHAR szImeRegFmt[] = L"System\\CurrentControlSet\\Control\\Keyboard Layouts\\%08lx";
 
-static CRITICAL_SECTION threaddata_cs;
-static CRITICAL_SECTION_DEBUG critsect_debug =
-{
-    0, 0, &threaddata_cs,
-    { &critsect_debug.ProcessLocksList, &critsect_debug.ProcessLocksList },
-      0, 0, { (DWORD_PTR)(__FILE__ ": threaddata_cs") }
-};
-static CRITICAL_SECTION threaddata_cs = { &critsect_debug, -1, 0, 0, 0, 0 };
-static BOOL disable_ime;
-
 static inline BOOL is_himc_ime_unicode(const InputContextData *data)
 {
     return !!(data->immKbd->imeInfo.fdwProperty & IME_PROP_UNICODE);
@@ -412,38 +393,6 @@ static void imm_coinit_thread(void)
         spy->apt_flags |= IMM_APT_CREATED;
 }
 
-static IMMThreadData *IMM_GetThreadData(HWND hwnd, DWORD thread)
-{
-    IMMThreadData *data;
-    DWORD process;
-
-    if (hwnd)
-    {
-        if (!(thread = GetWindowThreadProcessId(hwnd, &process))) return NULL;
-        if (process != GetCurrentProcessId()) return NULL;
-    }
-    else if (thread)
-    {
-        HANDLE h = OpenThread(THREAD_QUERY_INFORMATION, FALSE, thread);
-        if (!h) return NULL;
-        process = GetProcessIdOfThread(h);
-        CloseHandle(h);
-        if (process != GetCurrentProcessId()) return NULL;
-    }
-    else
-        thread = GetCurrentThreadId();
-
-    EnterCriticalSection(&threaddata_cs);
-    LIST_FOR_EACH_ENTRY(data, &ImmThreadDataList, IMMThreadData, entry)
-        if (data->threadID == thread) return data;
-
-    data = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*data));
-    data->threadID = thread;
-    list_add_head(&ImmThreadDataList,&data->entry);
-    TRACE("Thread Data Created (%lx)\n",thread);
-    return data;
-}
-
 static BOOL IMM_IsDefaultContext(HIMC imc)
 {
     InputContextData *data = get_imc_data(imc);
@@ -490,21 +439,6 @@ static BOOL free_input_context_data(HIMC hIMC)
 static void IMM_FreeThreadData(void)
 {
     struct coinit_spy *spy;
-    IMMThreadData *data;
-
-    EnterCriticalSection(&threaddata_cs);
-    LIST_FOR_EACH_ENTRY(data, &ImmThreadDataList, IMMThreadData, entry)
-    {
-        if (data->threadID == GetCurrentThreadId())
-        {
-            list_remove(&data->entry);
-            LeaveCriticalSection(&threaddata_cs);
-            HeapFree(GetProcessHeap(),0,data);
-            TRACE("Thread Data Destroyed\n");
-            return;
-        }
-    }
-    LeaveCriticalSection(&threaddata_cs);
 
     free_input_context_data(NtUserGetThreadInfo()->default_imc);
     if ((spy = get_thread_coinit_spy()))
@@ -981,62 +915,6 @@ BOOL WINAPI ImmDestroyContext(HIMC hIMC)
         return FALSE;
 }
 
-static HWND imm_detach_default_window(IMMThreadData *thread_data)
-{
-    HWND to_destroy;
-
-    to_destroy = thread_data->hwndDefault;
-    thread_data->hwndDefault = NULL;
-    thread_data->windowRefs = 0;
-    return to_destroy;
-}
-
-/***********************************************************************
- *		ImmDisableIME (IMM32.@)
- */
-BOOL WINAPI ImmDisableIME(DWORD idThread)
-{
-    IMMThreadData *thread_data;
-    HWND to_destroy;
-
-    if (idThread == (DWORD)-1)
-    {
-        disable_ime = TRUE;
-
-        while (1)
-        {
-            to_destroy = 0;
-            EnterCriticalSection(&threaddata_cs);
-            LIST_FOR_EACH_ENTRY(thread_data, &ImmThreadDataList, IMMThreadData, entry)
-            {
-                if (thread_data->hwndDefault)
-                {
-                    to_destroy = imm_detach_default_window(thread_data);
-                    break;
-                }
-            }
-            LeaveCriticalSection(&threaddata_cs);
-
-            if (!to_destroy)
-                break;
-            DestroyWindow(to_destroy);
-        }
-    }
-    else if (!idThread || idThread == GetCurrentThreadId())
-    {
-        thread_data = IMM_GetThreadData(NULL, idThread);
-        if (!thread_data) return FALSE;
-        thread_data->disableIME = TRUE;
-        to_destroy = imm_detach_default_window(thread_data);
-        LeaveCriticalSection(&threaddata_cs);
-
-        if (to_destroy)
-            DestroyWindow(to_destroy);
-    }
-    else return FALSE;
-    return TRUE;
-}
-
 /***********************************************************************
  *		ImmEnumRegisterWordA (IMM32.@)
  */
@@ -1816,107 +1694,12 @@ BOOL WINAPI ImmGetConversionStatus(
     return TRUE;
 }
 
-static BOOL needs_ime_window(HWND hwnd)
-{
-    WCHAR classW[8];
-
-    if (GetClassNameW(hwnd, classW, ARRAY_SIZE(classW)) && !lstrcmpW(classW, L"IME"))
-        return FALSE;
-    if (GetClassLongPtrW(hwnd, GCL_STYLE) & CS_IME) return FALSE;
-
-    return TRUE;
-}
-
-/***********************************************************************
- *		__wine_register_window (IMM32.@)
- */
-BOOL WINAPI __wine_register_window(HWND hwnd)
-{
-    HWND new = NULL;
-    IMMThreadData *thread_data;
-    TRACE("(%p)\n", hwnd);
-
-    if (!needs_ime_window(hwnd))
-        return FALSE;
-
-    thread_data = IMM_GetThreadData(hwnd, 0);
-    if (!thread_data)
-        return FALSE;
-
-    if (thread_data->disableIME || disable_ime)
-    {
-        TRACE("IME for this thread is disabled\n");
-        LeaveCriticalSection(&threaddata_cs);
-        return FALSE;
-    }
-    thread_data->windowRefs++;
-    TRACE("windowRefs=%lu, hwndDefault=%p\n",
-          thread_data->windowRefs, thread_data->hwndDefault);
-
-    /* Create default IME window */
-    if (thread_data->windowRefs == 1)
-    {
-        /* Do not create the window inside of a critical section */
-        LeaveCriticalSection(&threaddata_cs);
-        new = CreateWindowExW( 0, L"IME", L"Default IME",
-                               WS_POPUP | WS_DISABLED | WS_CLIPSIBLINGS,
-                               0, 0, 1, 1, 0, 0, 0, 0);
-        /* thread_data is in the current thread so we can assume it's still valid */
-        EnterCriticalSection(&threaddata_cs);
-        /* See if anyone beat us */
-        if (thread_data->hwndDefault == NULL)
-        {
-            thread_data->hwndDefault = new;
-            new = NULL;
-            TRACE("Default is %p\n", thread_data->hwndDefault);
-        }
-    }
-
-    LeaveCriticalSection(&threaddata_cs);
-
-    /* Clean up an unused new window outside of the critical section */
-    if (new != NULL)
-        DestroyWindow(new);
-    return TRUE;
-}
-
-/***********************************************************************
- *		__wine_unregister_window (IMM32.@)
- */
-void WINAPI __wine_unregister_window(HWND hwnd)
-{
-    HWND to_destroy = 0;
-    IMMThreadData *thread_data;
-    TRACE("(%p)\n", hwnd);
-
-    thread_data = IMM_GetThreadData(hwnd, 0);
-    if (!thread_data) return;
-
-    thread_data->windowRefs--;
-    TRACE("windowRefs=%lu, hwndDefault=%p\n",
-          thread_data->windowRefs, thread_data->hwndDefault);
-
-    /* Destroy default IME window */
-    if (thread_data->windowRefs == 0)
-        to_destroy = imm_detach_default_window(thread_data);
-    LeaveCriticalSection(&threaddata_cs);
-
-    if (to_destroy) DestroyWindow( to_destroy );
-}
-
 /***********************************************************************
  *		ImmGetDefaultIMEWnd (IMM32.@)
  */
 HWND WINAPI ImmGetDefaultIMEWnd(HWND hWnd)
 {
-    HWND ret;
-    IMMThreadData* thread_data = IMM_GetThreadData(hWnd, 0);
-    if (!thread_data)
-        return NULL;
-    ret = thread_data->hwndDefault;
-    LeaveCriticalSection(&threaddata_cs);
-    TRACE("Default is %p\n",ret);
-    return ret;
+    return NtUserGetDefaultImeWindow(hWnd);
 }
 
 /***********************************************************************
diff --git a/dlls/imm32/imm32.spec b/dlls/imm32/imm32.spec
index e95731183ea..70b8aef3a95 100644
--- a/dlls/imm32/imm32.spec
+++ b/dlls/imm32/imm32.spec
@@ -9,8 +9,8 @@
 @ stdcall ImmDestroyContext(long)
 @ stdcall ImmDestroyIMCC(long)
 @ stdcall ImmDestroySoftKeyboard(long)
-@ stdcall ImmDisableIME(long)
-@ stdcall ImmDisableIme(long) ImmDisableIME
+@ stdcall ImmDisableIME(long) NtUserDisableThreadIme
+@ stdcall ImmDisableIme(long) NtUserDisableThreadIme
 @ stdcall ImmDisableLegacyIME()
 @ stdcall ImmDisableTextFrameService(long)
 @ stdcall ImmEnumInputContext(long ptr long)
@@ -115,5 +115,3 @@
 ################################################################
 # Wine internal extensions
 @ stdcall __wine_ime_wnd_proc(long long long long long)
-@ stdcall __wine_register_window(long)
-@ stdcall __wine_unregister_window(long)
diff --git a/dlls/imm32/tests/imm32.c b/dlls/imm32/tests/imm32.c
index c5409ce1708..17369ca9102 100644
--- a/dlls/imm32/tests/imm32.c
+++ b/dlls/imm32/tests/imm32.c
@@ -2426,11 +2426,9 @@ static void test_ImmDisableIME(void)
 
     ok(IsWindow(def), "not a window\n");
     def2 = ImmGetDefaultIMEWnd(hwnd);
-    todo_wine
     ok(def2 == def, "ImmGetDefaultIMEWnd(hwnd) returned %p\n", def2);
     ok(IsWindow(def), "not a window\n");
     msg_spy_pump_msg_queue();
-    todo_wine
     ok(!IsWindow(def), "window is still valid\n");
     def = ImmGetDefaultIMEWnd(hwnd);
     ok(!def, "ImmGetDefaultIMEWnd(hwnd) returned %p\n", def);
diff --git a/dlls/user32/misc.c b/dlls/user32/misc.c
index 31ec85c36eb..64a300f83ef 100644
--- a/dlls/user32/misc.c
+++ b/dlls/user32/misc.c
@@ -39,8 +39,6 @@ BOOL WINAPI ImmSetActiveContext(HWND, HIMC, BOOL);
 
 #define IMM_INIT_MAGIC 0x19650412
 static LRESULT (WINAPI *imm_ime_wnd_proc)( HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam, BOOL ansi);
-BOOL (WINAPI *imm_register_window)(HWND) = NULL;
-void (WINAPI *imm_unregister_window)(HWND) = NULL;
 
 /* USER signal proc flags and codes */
 /* See UserSignalProc for comments */
@@ -328,8 +326,6 @@ BOOL WINAPI User32InitializeImmEntryTable(DWORD magic)
 
     /* this part is not compatible with native imm32.dll */
     imm_ime_wnd_proc = (void*)GetProcAddress(imm32, "__wine_ime_wnd_proc");
-    imm_register_window = (void*)GetProcAddress(imm32, "__wine_register_window");
-    imm_unregister_window = (void*)GetProcAddress(imm32, "__wine_unregister_window");
     if (!imm_ime_wnd_proc)
         FIXME("native imm32.dll not supported\n");
     return TRUE;
diff --git a/dlls/user32/user_main.c b/dlls/user32/user_main.c
index 26427bd2cf6..ae6a0d4c8e4 100644
--- a/dlls/user32/user_main.c
+++ b/dlls/user32/user_main.c
@@ -119,22 +119,6 @@ static void dpiaware_init(void)
     }
 }
 
-static void CDECL notify_ime( HWND hwnd, UINT param )
-{
-    HWND ime_default = ImmGetDefaultIMEWnd( hwnd );
-    if (ime_default) SendMessageW( ime_default, WM_IME_INTERNAL, param, HandleToUlong(hwnd) );
-}
-
-static BOOL WINAPI register_imm( HWND hwnd )
-{
-    return imm_register_window( hwnd );
-}
-
-static void WINAPI unregister_imm( HWND hwnd )
-{
-    imm_unregister_window( hwnd );
-}
-
 static NTSTATUS try_finally( NTSTATUS (CDECL *func)( void *), void *arg,
                              void (CALLBACK *finally_func)( BOOL ))
 {
@@ -152,11 +136,8 @@ static const struct user_callbacks user_funcs =
     ImmProcessKey,
     ImmTranslateMessage,
     NtWaitForMultipleObjects,
-    notify_ime,
     post_dde_message,
     unpack_dde_message,
-    register_imm,
-    unregister_imm,
     try_finally,
 };
 
diff --git a/dlls/user32/user_private.h b/dlls/user32/user_private.h
index 3be5b84b41b..e637bf01f5e 100644
--- a/dlls/user32/user_private.h
+++ b/dlls/user32/user_private.h
@@ -47,9 +47,6 @@ struct wm_char_mapping_data
     MSG  get_msg;
 };
 
-extern BOOL (WINAPI *imm_register_window)(HWND) DECLSPEC_HIDDEN;
-extern void (WINAPI *imm_unregister_window)(HWND) DECLSPEC_HIDDEN;
-
 static inline struct user_thread_info *get_user_thread_info(void)
 {
     return (struct user_thread_info *)NtCurrentTeb()->Win32ClientInfo;
diff --git a/dlls/win32u/class.c b/dlls/win32u/class.c
index 5af9e586e01..6a3f039bc3b 100644
--- a/dlls/win32u/class.c
+++ b/dlls/win32u/class.c
@@ -1007,6 +1007,18 @@ WORD get_class_word( HWND hwnd, INT offset )
     return retvalue;
 }
 
+BOOL needs_ime_window( HWND hwnd )
+{
+    static const WCHAR imeW[] = {'I','M','E',0};
+    CLASS *class;
+    BOOL ret;
+
+    if (!(class = get_class_ptr( hwnd, FALSE ))) return FALSE;
+    ret = !(class->style & CS_IME) && wcscmp( imeW, class->name );
+    release_class_ptr( class );
+    return ret;
+}
+
 static void register_builtins(void)
 {
     void *ret_ptr;
diff --git a/dlls/win32u/gdiobj.c b/dlls/win32u/gdiobj.c
index 9aab651e551..fddaf898761 100644
--- a/dlls/win32u/gdiobj.c
+++ b/dlls/win32u/gdiobj.c
@@ -1157,6 +1157,7 @@ static struct unix_funcs unix_funcs =
     NtUserDestroyCursor,
     NtUserDestroyMenu,
     NtUserDestroyWindow,
+    NtUserDisableThreadIme,
     NtUserDispatchMessage,
     NtUserDragDetect,
     NtUserDrawCaptionTemp,
diff --git a/dlls/win32u/imm.c b/dlls/win32u/imm.c
index c0fe5887ffd..94621bb2a5c 100644
--- a/dlls/win32u/imm.c
+++ b/dlls/win32u/imm.c
@@ -1,6 +1,8 @@
 /*
  * Input Context implementation
  *
+ * Copyright 1998 Patrik Stridvall
+ * Copyright 2002, 2003, 2007 CodeWeavers, Aric Stewart
  * Copyright 2022 Jacek Caban for CodeWeavers
  *
  * This library is free software; you can redistribute it and/or
@@ -22,6 +24,7 @@
 #pragma makedep unix
 #endif
 
+#include <pthread.h>
 #include "win32u_private.h"
 #include "ntuser_private.h"
 #include "wine/debug.h"
@@ -36,6 +39,18 @@ struct imc
     UINT_PTR client_ptr;
 };
 
+struct imm_thread_data
+{
+    struct list entry;
+    DWORD thread_id;
+    HWND  default_hwnd;
+    BOOL  disable_ime;
+    UINT  window_cnt;
+};
+
+static struct list thread_data_list = LIST_INIT( thread_data_list );
+static pthread_mutex_t imm_mutex = PTHREAD_MUTEX_INITIALIZER;
+static BOOL disable_ime;
 
 static struct imc *get_imc_ptr( HIMC handle )
 {
@@ -215,3 +230,164 @@ HIMC get_window_input_context( HWND hwnd )
     release_win_ptr( win );
     return ret;
 }
+
+static HWND detach_default_window( struct imm_thread_data *thread_data )
+{
+    HWND hwnd = thread_data->default_hwnd;
+    thread_data->default_hwnd = NULL;
+    thread_data->window_cnt = 0;
+    return hwnd;
+}
+
+static struct imm_thread_data *get_imm_thread_data(void)
+{
+    struct user_thread_info *thread_info = get_user_thread_info();
+    if (!thread_info->imm_thread_data)
+    {
+        struct imm_thread_data *data;
+        if (!(data = calloc( 1, sizeof( *data )))) return NULL;
+        data->thread_id = GetCurrentThreadId();
+
+        pthread_mutex_lock( &imm_mutex );
+        list_add_tail( &thread_data_list, &data->entry );
+        pthread_mutex_unlock( &imm_mutex );
+
+        thread_info->imm_thread_data = data;
+    }
+    return thread_info->imm_thread_data;
+}
+
+BOOL register_imm_window( HWND hwnd )
+{
+    struct imm_thread_data *thread_data;
+
+    TRACE( "(%p)\n", hwnd );
+
+    if (disable_ime || !needs_ime_window( hwnd ))
+        return FALSE;
+
+    thread_data = get_imm_thread_data();
+    if (!thread_data || thread_data->disable_ime)
+        return FALSE;
+
+    TRACE( "window_cnt=%u, default_hwnd=%p\n", thread_data->window_cnt + 1, thread_data->default_hwnd );
+
+    /* Create default IME window */
+    if (!thread_data->window_cnt++)
+    {
+        UNICODE_STRING class_name, name;
+        static const WCHAR imeW[] = {'I','M','E',0};
+        static const WCHAR default_imeW[] = {'D','e','f','a','u','l','t',' ','I','M','E',0};
+
+        RtlInitUnicodeString( &class_name, imeW );
+        RtlInitUnicodeString( &name, default_imeW );
+        thread_data->default_hwnd = NtUserCreateWindowEx( 0, &class_name, &class_name, &name,
+                                                          WS_POPUP | WS_DISABLED | WS_CLIPSIBLINGS,
+                                                          0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, FALSE );
+    }
+
+    return TRUE;
+}
+
+void unregister_imm_window( HWND hwnd )
+{
+    struct imm_thread_data *thread_data = get_user_thread_info()->imm_thread_data;
+
+    if (!thread_data) return;
+    if (thread_data->default_hwnd == hwnd)
+    {
+        detach_default_window( thread_data );
+        return;
+    }
+
+    if (!(win_set_flags( hwnd, 0, WIN_HAS_IME_WIN ) & WIN_HAS_IME_WIN)) return;
+
+    /* destroy default IME window */
+    TRACE( "unregister IME window for %p\n", hwnd );
+    if (!--thread_data->window_cnt)
+    {
+        HWND destroy_hwnd = detach_default_window( thread_data );
+        if (destroy_hwnd) NtUserDestroyWindow( destroy_hwnd );
+    }
+}
+
+/***********************************************************************
+ *           NtUserDisableThreadIme (win32u.@)
+ */
+BOOL WINAPI NtUserDisableThreadIme( DWORD thread_id )
+{
+    struct imm_thread_data *thread_data;
+
+    if (thread_id == -1)
+    {
+        disable_ime = TRUE;
+
+        pthread_mutex_lock( &imm_mutex );
+        LIST_FOR_EACH_ENTRY( thread_data, &thread_data_list, struct imm_thread_data, entry )
+        {
+            if (thread_data->thread_id == GetCurrentThreadId()) continue;
+            if (!thread_data->default_hwnd) continue;
+            NtUserMessageCall( thread_data->default_hwnd, WM_WINE_DESTROYWINDOW, 0, 0,
+                               0, NtUserSendNotifyMessage, FALSE );
+        }
+        pthread_mutex_unlock( &imm_mutex );
+    }
+    else if (!thread_id || thread_id == GetCurrentThreadId())
+    {
+        if (!(thread_data = get_imm_thread_data())) return FALSE;
+        thread_data->disable_ime = TRUE;
+    }
+    else return FALSE;
+
+    if ((thread_data = get_user_thread_info()->imm_thread_data))
+    {
+        HWND destroy_hwnd = detach_default_window( thread_data );
+        NtUserDestroyWindow( destroy_hwnd );
+    }
+    return TRUE;
+}
+
+HWND get_default_ime_window( HWND hwnd )
+{
+    struct imm_thread_data *thread_data;
+    HWND ret = 0;
+
+    if (hwnd)
+    {
+        DWORD thread_id;
+
+        if (!(thread_id = get_window_thread( hwnd, NULL ))) return 0;
+
+        pthread_mutex_lock( &imm_mutex );
+        LIST_FOR_EACH_ENTRY( thread_data, &thread_data_list, struct imm_thread_data, entry )
+        {
+            if (thread_data->thread_id != thread_id) continue;
+            ret = thread_data->default_hwnd;
+            break;
+        }
+        pthread_mutex_unlock( &imm_mutex );
+    }
+    else if ((thread_data = get_user_thread_info()->imm_thread_data))
+    {
+        ret = thread_data->default_hwnd;
+    }
+
+    TRACE( "default for %p is %p\n", hwnd, ret );
+    return ret;
+}
+
+void cleanup_imm_thread(void)
+{
+    struct user_thread_info *thread_info = get_user_thread_info();
+
+    if (thread_info->imm_thread_data)
+    {
+        pthread_mutex_lock( &imm_mutex );
+        list_remove( &thread_info->imm_thread_data->entry );
+        pthread_mutex_unlock( &imm_mutex );
+        free( thread_info->imm_thread_data );
+        thread_info->imm_thread_data = NULL;
+    }
+
+    NtUserDestroyInputContext( thread_info->client_info.default_imc );
+}
diff --git a/dlls/win32u/input.c b/dlls/win32u/input.c
index 6f0e4f45501..c41a41c605a 100644
--- a/dlls/win32u/input.c
+++ b/dlls/win32u/input.c
@@ -1551,7 +1551,7 @@ HWND get_focus(void)
  */
 static HWND set_focus_window( HWND hwnd )
 {
-    HWND previous = 0;
+    HWND previous = 0, ime_hwnd;
     BOOL ret;
 
     SERVER_START_REQ( set_focus_window )
@@ -1568,7 +1568,10 @@ static HWND set_focus_window( HWND hwnd )
     {
         send_message( previous, WM_KILLFOCUS, (WPARAM)hwnd, 0 );
 
-        if (user_callbacks) user_callbacks->notify_ime( previous, IME_INTERNAL_DEACTIVATE );
+        ime_hwnd = get_default_ime_window( previous );
+        if (ime_hwnd)
+            send_message( ime_hwnd, WM_IME_INTERNAL, IME_INTERNAL_DEACTIVATE,
+                          HandleToUlong(previous) );
 
         if (hwnd != get_focus()) return previous;  /* changed by the message */
     }
@@ -1576,7 +1579,10 @@ static HWND set_focus_window( HWND hwnd )
     {
         user_driver->pSetFocus(hwnd);
 
-        if (user_callbacks) user_callbacks->notify_ime( hwnd, IME_INTERNAL_ACTIVATE );
+        ime_hwnd = get_default_ime_window( hwnd );
+        if (ime_hwnd)
+            send_message( ime_hwnd, WM_IME_INTERNAL, IME_INTERNAL_ACTIVATE,
+                          HandleToUlong(hwnd) );
 
         if (previous)
             NtUserNotifyWinEvent( EVENT_OBJECT_FOCUS, hwnd, OBJID_CLIENT, 0 );
diff --git a/dlls/win32u/ntuser_private.h b/dlls/win32u/ntuser_private.h
index ba1c0b68d17..780af425673 100644
--- a/dlls/win32u/ntuser_private.h
+++ b/dlls/win32u/ntuser_private.h
@@ -35,13 +35,10 @@ struct user_callbacks
     BOOL (WINAPI *pImmProcessKey)(HWND, HKL, UINT, LPARAM, DWORD);
     BOOL (WINAPI *pImmTranslateMessage)(HWND, UINT, WPARAM, LPARAM);
     NTSTATUS (WINAPI *pNtWaitForMultipleObjects)(ULONG,const HANDLE*,BOOLEAN,BOOLEAN,const LARGE_INTEGER*);
-    void (CDECL *notify_ime)( HWND hwnd, UINT param );
     BOOL (CDECL *post_dde_message)( HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam, DWORD dest_tid,
                                     DWORD type );
     BOOL (CDECL *unpack_dde_message)( HWND hwnd, UINT message, WPARAM *wparam, LPARAM *lparam,
                                       void **buffer, size_t size );
-    BOOL (WINAPI *register_imm)( HWND hwnd );
-    void (WINAPI *unregister_imm)( HWND hwnd );
     NTSTATUS (CDECL *try_finally)( NTSTATUS (CDECL *func)( void *), void *arg,
                                    void (CALLBACK *finally_func)( BOOL ));
 };
@@ -154,6 +151,7 @@ struct user_thread_info
     struct received_message_info *receive_info;           /* Message being currently received */
     struct wm_char_mapping_data  *wmchar_data;            /* Data for WM_CHAR mappings */
     struct user_key_state_info   *key_state;              /* Cache of global key state */
+    struct imm_thread_data       *imm_thread_data;        /* IMM thread data */
     HKL                           kbd_layout;             /* Current keyboard layout */
     DWORD                         kbd_layout_id;          /* Current keyboard layout ID */
     struct rawinput_thread_data  *rawinput;               /* RawInput thread local data / buffer */
@@ -273,6 +271,7 @@ WNDPROC get_winproc( WNDPROC proc, BOOL ansi ) DECLSPEC_HIDDEN;
 void get_winproc_params( struct win_proc_params *params ) DECLSPEC_HIDDEN;
 struct dce *get_class_dce( struct tagCLASS *class ) DECLSPEC_HIDDEN;
 struct dce *set_class_dce( struct tagCLASS *class, struct dce *dce ) DECLSPEC_HIDDEN;
+BOOL needs_ime_window( HWND hwnd ) DECLSPEC_HIDDEN;
 extern void register_builtin_classes(void) DECLSPEC_HIDDEN;
 
 /* cursoricon.c */
diff --git a/dlls/win32u/sysparams.c b/dlls/win32u/sysparams.c
index 69e39713102..2c1f8f4241f 100644
--- a/dlls/win32u/sysparams.c
+++ b/dlls/win32u/sysparams.c
@@ -4818,7 +4818,7 @@ static void thread_detach(void)
     free( thread_info->rawinput );
 
     destroy_thread_windows();
-    NtUserDestroyInputContext( thread_info->client_info.default_imc );
+    cleanup_imm_thread();
     NtClose( thread_info->server_queue );
 
     exiting_thread_id = 0;
diff --git a/dlls/win32u/win32u.spec b/dlls/win32u/win32u.spec
index 313361989ec..d74685ad603 100644
--- a/dlls/win32u/win32u.spec
+++ b/dlls/win32u/win32u.spec
@@ -837,7 +837,7 @@
 @ stdcall NtUserDestroyWindow(long)
 @ stub NtUserDisableImmersiveOwner
 @ stub NtUserDisableProcessWindowFiltering
-@ stub NtUserDisableThreadIme
+@ stdcall NtUserDisableThreadIme(long)
 @ stub NtUserDiscardPointerFrameMessages
 @ stdcall NtUserDispatchMessage(ptr)
 @ stub NtUserDisplayConfigGetDeviceInfo
diff --git a/dlls/win32u/win32u_private.h b/dlls/win32u/win32u_private.h
index 1f7bcb9e2e3..a0b3e8c2e9e 100644
--- a/dlls/win32u/win32u_private.h
+++ b/dlls/win32u/win32u_private.h
@@ -214,6 +214,7 @@ struct unix_funcs
     BOOL     (WINAPI *pNtUserDestroyCursor)( HCURSOR cursor, ULONG arg );
     BOOL     (WINAPI *pNtUserDestroyMenu)( HMENU handle );
     BOOL     (WINAPI *pNtUserDestroyWindow)( HWND hwnd );
+    BOOL     (WINAPI *pNtUserDisableThreadIme)( DWORD thread_id );
     LRESULT  (WINAPI *pNtUserDispatchMessage)( const MSG *msg );
     BOOL     (WINAPI *pNtUserDragDetect)( HWND hwnd, int x, int y );
     BOOL     (WINAPI *pNtUserDrawCaptionTemp)( HWND hwnd, HDC hdc, const RECT *rect, HFONT font,
@@ -393,8 +394,12 @@ extern LRESULT call_hooks( INT id, INT code, WPARAM wparam, LPARAM lparam, BOOL
 extern BOOL unhook_windows_hook( INT id, HOOKPROC proc ) DECLSPEC_HIDDEN;
 
 /* imm.c */
+extern void cleanup_imm_thread(void) DECLSPEC_HIDDEN;
+extern HWND get_default_ime_window( HWND hwnd ) DECLSPEC_HIDDEN;
 extern HIMC get_default_input_context(void) DECLSPEC_HIDDEN;
 extern HIMC get_window_input_context( HWND hwnd ) DECLSPEC_HIDDEN;
+extern BOOL register_imm_window( HWND hwnd ) DECLSPEC_HIDDEN;
+extern void unregister_imm_window( HWND hwnd ) DECLSPEC_HIDDEN;
 
 /* input.c */
 extern BOOL destroy_caret(void) DECLSPEC_HIDDEN;
diff --git a/dlls/win32u/window.c b/dlls/win32u/window.c
index a8fca0678d0..fee1617ef10 100644
--- a/dlls/win32u/window.c
+++ b/dlls/win32u/window.c
@@ -4680,12 +4680,7 @@ LRESULT destroy_window( HWND hwnd )
 
     TRACE( "%p\n", hwnd );
 
-    /* destroy default IME window */
-    if (win_set_flags( hwnd, 0, WIN_HAS_IME_WIN ) & WIN_HAS_IME_WIN)
-    {
-        TRACE("unregister IME window for %p\n", hwnd);
-        if (user_callbacks) user_callbacks->unregister_imm( hwnd );
-    }
+    unregister_imm_window( hwnd );
 
     /* free child windows */
     if ((children = list_window_children( 0, hwnd, NULL, 0 )))
@@ -5262,7 +5257,7 @@ HWND WINAPI NtUserCreateWindowEx( DWORD ex_style, UNICODE_STRING *class_name,
     /* create default IME window */
 
     if (!is_desktop_window( hwnd ) && parent != get_hwnd_message_parent() &&
-        user_callbacks && user_callbacks->register_imm( hwnd ))
+        register_imm_window( hwnd ))
     {
         TRACE( "register IME window for %p\n", hwnd );
         win_set_flags( hwnd, WIN_HAS_IME_WIN, 0 );
@@ -5377,6 +5372,9 @@ ULONG_PTR WINAPI NtUserCallHwnd( HWND hwnd, DWORD code )
     case NtUserCallHwnd_DrawMenuBar:
         return draw_menu_bar( hwnd );
 
+    case NtUserCallHwnd_GetDefaultImeWindow:
+        return HandleToUlong( get_default_ime_window( hwnd ));
+
     case NtUserCallHwnd_GetDpiForWindow:
         return get_dpi_for_window( hwnd );
 
diff --git a/dlls/win32u/wrappers.c b/dlls/win32u/wrappers.c
index ba6fa9ea0a0..609e893403b 100644
--- a/dlls/win32u/wrappers.c
+++ b/dlls/win32u/wrappers.c
@@ -849,6 +849,12 @@ BOOL WINAPI NtUserDestroyWindow( HWND hwnd )
     return unix_funcs->pNtUserDestroyWindow( hwnd );
 }
 
+BOOL WINAPI NtUserDisableThreadIme( DWORD thread_id )
+{
+    if (!unix_funcs) return FALSE;
+    return unix_funcs->pNtUserDisableThreadIme( thread_id );
+}
+
 LRESULT WINAPI NtUserDispatchMessage( const MSG *msg )
 {
     if (!unix_funcs) return 0;
diff --git a/include/ntuser.h b/include/ntuser.h
index 0528e0d90bf..281d88dfb1a 100644
--- a/include/ntuser.h
+++ b/include/ntuser.h
@@ -599,6 +599,7 @@ BOOL    WINAPI NtUserDestroyCursor( HCURSOR cursor, ULONG arg );
 BOOL    WINAPI NtUserDestroyInputContext( HIMC handle );
 BOOL    WINAPI NtUserDestroyMenu( HMENU menu );
 BOOL    WINAPI NtUserDestroyWindow( HWND hwnd );
+BOOL    WINAPI NtUserDisableThreadIme( DWORD thread_id );
 LRESULT WINAPI NtUserDispatchMessage( const MSG *msg );
 BOOL    WINAPI NtUserDragDetect( HWND hwnd, int x, int y );
 BOOL    WINAPI NtUserDrawCaptionTemp( HWND hwnd, HDC hdc, const RECT *rect, HFONT font,
@@ -1055,6 +1056,7 @@ enum
 {
     NtUserCallHwnd_ArrangeIconicWindows,
     NtUserCallHwnd_DrawMenuBar,
+    NtUserCallHwnd_GetDefaultImeWindow,
     NtUserCallHwnd_GetDpiForWindow,
     NtUserCallHwnd_GetParent,
     NtUserCallHwnd_GetWindowContextHelpId,
@@ -1083,6 +1085,11 @@ static inline DWORD NtUserGetWindowContextHelpId( HWND hwnd )
     return NtUserCallHwnd( hwnd, NtUserCallHwnd_GetWindowContextHelpId );
 }
 
+static inline HWND NtUserGetDefaultImeWindow( HWND hwnd )
+{
+    return UlongToHandle( NtUserCallHwnd( hwnd, NtUserCallHwnd_GetDefaultImeWindow ));
+}
+
 static inline UINT NtUserGetDpiForWindow( HWND hwnd )
 {
     return NtUserCallHwnd( hwnd, NtUserCallHwnd_GetDpiForWindow );