diff --git a/include/gdi.h b/include/gdi.h
index dfe07c4f..1d14a58c 100644
--- a/include/gdi.h
+++ b/include/gdi.h
@@ -1886,7 +1886,7 @@ MG_EXPORT const char *GUIAPI GetSharedSurfaceInfo (HSURF surf, int *fd,
 /**
  * \fn BOOL GUIAPI LockSharedSurface (HSURF surf,
  *      unsigned *dirty_age, int *nr_dirty_rects, const RECT **dirty_rects)
- * \brief Locks the shared surface.
+ * \brief Locks the shared surface for read.
  *
  * This function lock the given shared surface \a surf and returns
  * the dirty age.
@@ -1911,25 +1911,22 @@ MG_EXPORT BOOL GUIAPI LockSharedSurface (HSURF surf,
         unsigned *dirty_age, int *nr_dirty_rects, const RECT **dirty_rects);
 
 /**
- * \fn BOOL GUIAPI UnlockSharedSurface (HSURF surf, BOOL clear_dirty)
- * \brief Unlocks the shared surface and clears the dirty information.
+ * \fn BOOL GUIAPI UnlockSharedSurface (HSURF surf)
+ * \brief Unlocks the shared surface.
  *
- * This function unlocks the shared surface \a surf, and clears its dirty
- * information if \a clear_dirty is TRUE.
+ * This function unlocks the given shared surface \a surf.
  *
  * \param surf The handle to the shared surface.
- * \param clear_dirty A boolean value indicates whether to clear the dirty
- *      information of the shared surface.
  *
  * \return TRUE on success; otherwise failure.
  *
  * \note This function only available when _MGSCHEMA_COMPOSITING is defined.
  *
- * \sa LockSharedSurfaceIfDirty
+ * \sa LockSharedSurface
  *
  * Since 5.2.0
  */
-MG_EXPORT BOOL GUIAPI UnlockSharedSurface (HSURF surf, BOOL clear_dirty);
+MG_EXPORT BOOL GUIAPI UnlockSharedSurface (HSURF surf);
 
 /**
  * \fn BOOL GUIAPI DetachFromSharedSurface (HSURF surf)
diff --git a/include/window.h b/include/window.h
index 2621eb90..2edca72a 100644
--- a/include/window.h
+++ b/include/window.h
@@ -2990,18 +2990,22 @@ typedef struct _WINMASKINFO {
    if the client moved to a new layer */
 #define MSG_LAYERCHANGED    0x0149
 
+/* Since 5.2.0; the server send this message to the client
+   if a window has been composited to the screen.  */
+#define MSG_WINCOMPOSITED   0x014A
+
 #endif /* defined _MGRM_PROCESSES */
 
 /* Since 5.0.0: for managing message thread */
-#define MSG_MANAGE_MSGTHREAD    0x014A
+#define MSG_MANAGE_MSGTHREAD    0x014B
     #define MSGTHREAD_SIGNIN        0x00
     #define MSGTHREAD_SIGNOUT       0x01
 
 /* Since 5.0.0: for calculating the default position */
-#define MSG_CALC_POSITION       0x014B
+#define MSG_CALC_POSITION       0x014C
 
 /* Since 5.0.6: for waking up the client */
-#define MSG_WAKEUP_CLIENT       0x014C
+#define MSG_WAKEUP_CLIENT       0x014D
 
 /**
  * \def MSG_DOESNEEDIME
diff --git a/src/client/client.c b/src/client/client.c
index cd1da6b9..0535c1cf 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -184,6 +184,21 @@ static void process_socket_message (MSG *msg)
                 LOSWORD(msg->wParam), HISWORD(msg->wParam),
                 LOSWORD(msg->lParam), HISWORD(msg->lParam));
     }
+#ifdef _MGSCHEMA_COMPOSITING
+    else if (msg->message == MSG_WINCOMPOSITED) {
+        /* Since 5.2.0 */
+        int slot = (int)msg->wParam;
+        HWND hwnd = (HWND)msg->lParam;
+        if (__mg_client_check_znode_hwnd(slot, hwnd, __mg_client_id)) {
+            GAL_Surface *ssurf = ((PMAINWIN)hwnd)->surf;
+            assert(ssurf->shared_header);
+            __mg_lock_file_for_write(ssurf->fd);
+            ssurf->dirty_info->nr_dirty_rcs = 0;
+            ssurf->dirty_info->dirty_age++;
+            __mg_unlock_file_for_write(ssurf->fd);
+        }
+    }
+#endif
     else {
         if (msg->hwnd == HWND_NULL) {
             msg->hwnd = HWND_DESKTOP;
diff --git a/src/include/client.h b/src/include/client.h
index 552af8a6..b9122b71 100644
--- a/src/include/client.h
+++ b/src/include/client.h
@@ -378,6 +378,7 @@ void __mg_start_client_desktop (void);
 
 void __mg_update_window (HWND hwnd, int left, int top, int right, int bottom);
 
+BOOL __mg_client_check_znode_hwnd (int slot, HWND hwnd, int cli);
 BOOL __mg_client_check_hwnd (HWND hwnd, int cli);
 BOOL __mg_client_on_layer_changed (GHANDLE layer_handle, int zi_shmid);
 
diff --git a/src/include/drawsemop.h b/src/include/drawsemop.h
index 907ee068..ba6b452a 100644
--- a/src/include/drawsemop.h
+++ b/src/include/drawsemop.h
@@ -82,21 +82,6 @@ again:
 
 extern int __mg_client_id;
 
-#if 0
-#ifdef _MGSCHEMA_COMPOSITING
-#   define LOCK_SURFACE_SEM(num)    \
-    do {  \
-        printf("Locking semaphor %d for client: %d\n", num, __mg_client_id);   \
-        my_sem_op(SHAREDRES_SEMID_SHARED_SURF, num, -1); \
-    } while (0)
-#   define UNLOCK_SURFACE_SEM(num)  \
-    do { \
-        my_sem_op(SHAREDRES_SEMID_SHARED_SURF, num, 1); \
-        printf("Unlocked semaphor %d for client: %d\n", num, __mg_client_id);   \
-    } while (0)
-#endif
-#endif
-
 #ifdef _MGHAVE_CURSOR
 
 #define LOCK_CURSOR_SEM()   my_sem_op(SHAREDRES_SEMID, _IDX_SEM_CURSOR, -1)
diff --git a/src/include/msgstr.h b/src/include/msgstr.h
index 94638a1f..4f753c90 100644
--- a/src/include/msgstr.h
+++ b/src/include/msgstr.h
@@ -396,10 +396,10 @@ char * __mg_msgstr3 [] =
     "MSG_SRVNOTIFY",          // 0x0147
     "MSG_UPDATECLIWIN",       // 0x0148
     "MSG_LAYERCHANGED",       // 0x0149
-    "MSG_MANAGE_MSGTHREAD",   // 0x014A
-    "MSG_CALC_POSITION",      // 0x014B
-    "",                       // 0x014C
-    "",                       // 0x014D
+    "MSG_WINCOMPOSITED",      // 0x014A
+    "MSG_MANAGE_MSGTHREAD",   // 0x014B
+    "MSG_CALC_POSITION",      // 0x014C
+    "MSG_WAKEUP_CLIENT",      // 0x014D
     "",                       // 0x014E
     "",                       // 0x014F
 
diff --git a/src/kernel/compsor-manager.c b/src/kernel/compsor-manager.c
index 81b0c1d9..fea53aaf 100644
--- a/src/kernel/compsor-manager.c
+++ b/src/kernel/compsor-manager.c
@@ -130,7 +130,6 @@ static const CompositorOps* load_default_compositor (void)
 
 static void lock_znode_surface (PDC pdc, ZORDERNODE* node)
 {
-    _DBG_PRINTF("lock count for node %p: %d\n", node, node->lock_count);
     if (node->lock_count == 0) {
         if (pdc->surface->shared_header) {
             __mg_lock_file_for_read(pdc->surface->fd);
@@ -145,12 +144,17 @@ static void lock_znode_surface (PDC pdc, ZORDERNODE* node)
     node->lock_count++;
 }
 
-static void unlock_znode_surface (PDC pdc, ZORDERNODE* node)
+static BOOL unlock_znode_surface (PDC pdc, ZORDERNODE* node)
 {
-    _DBG_PRINTF("lock count for node %p: %d\n", node, node->lock_count);
+    BOOL need_reset = FALSE;
     if (node->lock_count > 0) {
         node->lock_count--;
         if (node->lock_count == 0) {
+            if (node->changes != pdc->surface->dirty_info->dirty_age) {
+                node->changes = pdc->surface->dirty_info->dirty_age;
+                need_reset = TRUE;
+            }
+
             if (pdc->surface->shared_header) {
                 __mg_unlock_file_for_read(pdc->surface->fd);
             }
@@ -160,6 +164,19 @@ static void unlock_znode_surface (PDC pdc, ZORDERNODE* node)
             node->dirty_rcs = NULL;
         }
     }
+
+    return need_reset;
+}
+
+static void reset_znode_surface_dirty (PDC pdc, ZORDERNODE* node, int slot)
+{
+    if (node->cli == 0 || slot == 0) {
+        pdc->surface->dirty_info->nr_dirty_rcs = 0;
+    }
+    else if (node->hwnd) {
+        MSG msg = { HWND_NULL, MSG_WINCOMPOSITED, slot, (LPARAM)node->hwnd };
+        __mg_send2client(&msg, node);
+    }
 }
 
 #if 0   /* not optimized */
@@ -324,10 +341,8 @@ static void composite_layer (MG_Layer* layer, CompositorCtxt* ctxt,
         nodes = GET_MENUNODE(zi);
         for (i = 0; i < zi->nr_popupmenus; i++) {
             pdc = dc_HDC2PDC (nodes[i].mem_dc);
-
-            nodes[i].changes = pdc->surface->dirty_info->dirty_age;
-            pdc->surface->dirty_info->nr_dirty_rcs = 0;
-            unlock_znode_surface (pdc, nodes + i);
+            if (unlock_znode_surface (pdc, nodes + i))
+                reset_znode_surface_dirty (pdc, nodes + i, i);
         }
     }
 
@@ -337,9 +352,8 @@ static void composite_layer (MG_Layer* layer, CompositorCtxt* ctxt,
     while ((next = __kernel_get_next_znode (zi, next)) > 0) {
         if (nodes [next].flags & ZOF_VISIBLE) {
             pdc = dc_HDC2PDC (nodes[next].mem_dc);
-            nodes[next].changes = pdc->surface->dirty_info->dirty_age;
-            pdc->surface->dirty_info->nr_dirty_rcs = 0;
-            unlock_znode_surface (pdc, nodes + next);
+            if (unlock_znode_surface (pdc, nodes + next))
+                reset_znode_surface_dirty (pdc, nodes + next, next);
         }
     }
 
@@ -348,9 +362,8 @@ static void composite_layer (MG_Layer* layer, CompositorCtxt* ctxt,
     if (layer == mgTopmostLayer) {
         pdc = dc_HDC2PDC (HDC_SCREEN);
         if (pdc->surface->w > 0 && pdc->surface->h > 0) {
-            nodes[0].changes = pdc->surface->dirty_info->dirty_age;
-            pdc->surface->dirty_info->nr_dirty_rcs = 0;
-            unlock_znode_surface (pdc, nodes);
+            if (unlock_znode_surface (pdc, nodes))
+                reset_znode_surface_dirty (pdc, nodes, 0);
         }
     }
 }
diff --git a/src/kernel/desktop-comm.c b/src/kernel/desktop-comm.c
index 27677dec..afafea46 100644
--- a/src/kernel/desktop-comm.c
+++ b/src/kernel/desktop-comm.c
@@ -154,7 +154,7 @@ static int dskAllocZOrderNode (PMAINWIN pWin)
     return AllocZOrderNode (0, (HWND)pWin,
                 (HWND)pWin->pMainWin,
                 get_znode_flags_from_style (pWin),
-                &rc, pWin->spCaption, HDC_INVALID, -1,
+                &rc, pWin->spCaption, HDC_INVALID,
                 CT_OPAQUE, 0);
 }
 
diff --git a/src/kernel/desktop-procs.c b/src/kernel/desktop-procs.c
index 7067aaac..795ad32f 100644
--- a/src/kernel/desktop-procs.c
+++ b/src/kernel/desktop-procs.c
@@ -865,7 +865,7 @@ static int srvAllocZOrderNode (int cli, HWND hwnd, HWND main_win,
 #endif /* def _MGSCHEMA_COMPOSITING */
 
     free_slot = AllocZOrderNode (cli, hwnd,
-                    main_win, flags, rc, caption, memdc, fd, ct, ct_arg);
+                    main_win, flags, rc, caption, memdc, ct, ct_arg);
 
     if ((free_slot != -1) && OnZNodeOperation)
         OnZNodeOperation (ZNOP_ALLOCATE, cli, free_slot);
@@ -1020,7 +1020,7 @@ static int srvMoveWindow (int cli, int idx_znode, const RECT* rcWin,
     }
 #endif /* def _MGSCHEMA_COMPOSITING */
 
-    ret = dskMoveWindow (cli, idx_znode, memdc, fd, rcWin);
+    ret = dskMoveWindow (cli, idx_znode, memdc, rcWin);
     if (ret == 0 && OnZNodeOperation)
         OnZNodeOperation (ZNOP_MOVEWIN, cli, idx_znode);
 
@@ -2907,6 +2907,21 @@ int __mg_handle_mouse_hook (int message, WPARAM wParam, LPARAM lParam)
 }
 #endif  /* deprecated code */
 
+/* used by client to check the validation of a hwnd in the given znode slot. */
+BOOL __mg_client_check_znode_hwnd (int slot, HWND hwnd, int cli)
+{
+    BOOL ret = FALSE;
+    ZORDERINFO* zi = __mg_zorder_info;
+    ZORDERNODE* nodes;
+
+    nodes = GET_ZORDERNODE(zi);
+    lock_zi_for_read (zi);
+    if (nodes[slot].hwnd == hwnd && nodes[slot].cli == cli)
+        ret = TRUE;
+    unlock_zi_for_read (zi);
+    return ret;
+}
+
 /* used by client to check the validation of a hwnd */
 BOOL __mg_client_check_hwnd (HWND hwnd, int cli)
 {
diff --git a/src/kernel/desktop.c b/src/kernel/desktop.c
index 153be360..5ab17cb0 100644
--- a/src/kernel/desktop.c
+++ b/src/kernel/desktop.c
@@ -1648,6 +1648,7 @@ static int srvStartTrackPopupMenu (int cli, const RECT* rc, HWND ptmi,
     menu_nodes [zi->nr_popupmenus].flags = ZOF_TYPE_POPUPMENU;
     menu_nodes [zi->nr_popupmenus].rc = *rc;
     menu_nodes [zi->nr_popupmenus].hwnd = ptmi;
+    menu_nodes [zi->nr_popupmenus].cli = 0;
 #ifdef _MGSCHEMA_COMPOSITING
     menu_nodes [zi->nr_popupmenus].changes = 0;
     menu_nodes [zi->nr_popupmenus].ct = CT_OPAQUE;
@@ -2149,7 +2150,7 @@ static void update_on_new_visible_znode (void* layer, ZORDERINFO* zi,
 
 static int AllocZOrderNodeEx (ZORDERINFO* zi, int cli, HWND hwnd, HWND main_win,
                 DWORD flags, const RECT *rc, const char *caption,
-                HDC mem_dc, int fd, int ct, DWORD ct_arg)
+                HDC mem_dc, int ct, DWORD ct_arg)
 {
     DWORD type = flags & ZOF_TYPE_MASK;
     int *first = NULL, *nr_nodes = NULL;
@@ -2419,10 +2420,10 @@ static int AllocZOrderNodeEx (ZORDERINFO* zi, int cli, HWND hwnd, HWND main_win,
 
 static inline int AllocZOrderNode (int cli, HWND hwnd, HWND main_win,
                 DWORD flags, const RECT *rc, const char *caption,
-                HDC mem_dc, int fd, int ct, DWORD ct_arg)
+                HDC mem_dc, int ct, DWORD ct_arg)
 {
     return AllocZOrderNodeEx (get_zorder_info(cli), cli, hwnd, main_win,
-            flags, rc, caption, mem_dc, fd, ct, ct_arg);
+            flags, rc, caption, mem_dc, ct, ct_arg);
 }
 
 static void prepare_to_delete_visible_znode (void* layer, ZORDERINFO* zi,
@@ -3362,8 +3363,7 @@ static int dskHideWindow (int cli, int idx_znode)
     return 0;
 }
 
-static int dskMoveWindow (int cli, int idx_znode, HDC memdc, int fd,
-        const RECT* rcWin)
+static int dskMoveWindow (int cli, int idx_znode, HDC memdc, const RECT* rcWin)
 {
     DWORD type;
     int level, *first = NULL;
diff --git a/src/newgdi/shared-surface.c b/src/newgdi/shared-surface.c
index acd715e5..0c767a44 100644
--- a/src/newgdi/shared-surface.c
+++ b/src/newgdi/shared-surface.c
@@ -355,7 +355,7 @@ failed:
     return FALSE;
 }
 
-BOOL GUIAPI UnlockSharedSurface(HSURF surf, BOOL clear_dirty)
+BOOL GUIAPI UnlockSharedSurface(HSURF surf)
 {
     if (surf->shared_header == NULL) {
         _WRN_PRINTF("INVALID_ARG: surface handle: %p\n", surf);
@@ -363,11 +363,6 @@ BOOL GUIAPI UnlockSharedSurface(HSURF surf, BOOL clear_dirty)
     }
 
     __mg_unlock_file_for_read(surf->fd);
-
-    if (clear_dirty) {
-        surf->dirty_info->nr_dirty_rcs = 0;
-    }
-
     return TRUE;
 
 failed: