diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index a0192c44..94b537e0 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -28,8 +28,8 @@
 
 ## Version 5.0.10
 
-On Oct. 22 2022, FMSoft announces the availability of MiniGUI 5.0.10,
-which is a bug fixing release with minor enhancements of MiniGUI 5.0.x.
+On Sep. 15, 2022, FMSoft announces the availability of MiniGUI 5.0.10,
+which is a bug fixing release with some minor enhancements of MiniGUI 5.0.x.
 
 ### What's new in version 5.0.10
 
@@ -39,13 +39,13 @@ In this version, we made some enhancements
    - Enhance `fbcon` engine to support double buffering for Threads and Standalone mode. (Runtime option: `fbcon.double_buffering`).
    - Cleanup and enhance `shadow` engine to use `SyncUpdate` method.
 * BUGFIXING:
-   - Fix a deadlock bug: https://github.com/VincentWei/minigui/issues/83
+   - Fix a deadlock bug (Threads mode only): https://github.com/VincentWei/minigui/issues/83
 * OPTIMIZATIONS:
 * TUNING:
 
 ## Version 5.0.9
 
-On Jan. 14 2022, FMSoft announces the availability of MiniGUI 5.0.9,
+On Jan. 14, 2022, FMSoft announces the availability of MiniGUI 5.0.9,
 which is a bug fixing release with minor enhancements of MiniGUI 5.0.x.
 
 ### What's new in version 5.0.9
diff --git a/src/include/zorder.h b/src/include/zorder.h
index e9d12424..e5d43d81 100644
--- a/src/include/zorder.h
+++ b/src/include/zorder.h
@@ -141,13 +141,18 @@ typedef struct _ZORDERINFO {
     /* The size of usage bitmap for mask rect. */
     int             size_maskrect_usage_bmp;
 
+/* use read/write lock for Unix-like OS */
+#ifndef __NOUNIX__
+#define __ZI_USE_RWLOCK 1
+#endif
+
 #ifdef _MGRM_THREADS
-# ifndef __NOUNIX__
+# ifdef __ZI_USE_RWLOCK
     pthread_rwlock_t rwlock;
-# else
-    pthread_mutex_t  rwlock;
-# endif
     pthread_t        wrlock_owner;
+# else
+    pthread_mutex_t mutex;
+# endif
 #elif defined(_MGRM_PROCESSES)
     int             zi_semid;
     int             zi_semnum;
diff --git a/src/kernel/desktop.c b/src/kernel/desktop.c
index da68ff24..b583cbe7 100644
--- a/src/kernel/desktop.c
+++ b/src/kernel/desktop.c
@@ -597,65 +597,63 @@ static void reset_window (PMAINWIN pWin, RECT* rcWin)
 #endif
 
 #ifdef _MGRM_THREADS
-#ifndef __NOUNIX__
-/*for unix system, using read/write lock*/
-static inline void lock_zi_for_change (const ZORDERINFO* zi)
+# ifdef __ZI_USE_RWLOCK
+static inline void lock_zi_for_change (ZORDERINFO* zi)
 {
-    pthread_rwlock_wrlock(&((ZORDERINFO*)zi)->rwlock);
-    ((ZORDERINFO*)zi)->wrlock_owner = pthread_self();
+    pthread_rwlock_wrlock(&zi->rwlock);
+    zi->wrlock_owner = pthread_self();
 }
 
-static inline void unlock_zi_for_change (const ZORDERINFO* zi)
+static inline void unlock_zi_for_change (ZORDERINFO* zi)
 {
-    pthread_rwlock_unlock(&((ZORDERINFO*)zi)->rwlock);
-    ((ZORDERINFO*)zi)->wrlock_owner = 0;
+    pthread_rwlock_unlock(&zi->rwlock);
+    zi->wrlock_owner = 0;
 }
 
-static inline void lock_zi_for_read (const ZORDERINFO* zi)
+static inline void lock_zi_for_read (ZORDERINFO* zi)
 {
     if (zi->wrlock_owner == pthread_self()) {
         return;
     }
 
-    pthread_rwlock_rdlock(&((ZORDERINFO*)zi)->rwlock);
+    pthread_rwlock_rdlock(&zi->rwlock);
 }
 
-static inline void unlock_zi_for_read (const ZORDERINFO* zi)
+static inline void unlock_zi_for_read (ZORDERINFO* zi)
 {
     if (zi->wrlock_owner == pthread_self()) {
         return;
     }
 
-    pthread_rwlock_unlock(&((ZORDERINFO*)zi)->rwlock);
+    pthread_rwlock_unlock(&zi->rwlock);
 }
-#else /* __NOUNIX__ */
-/*for non-unix system, using mutex*/
-static inline void lock_zi_for_change (const ZORDERINFO* zi)
+# else /* __ZI_USE_RWLOCK */
+static inline void lock_zi_for_change (ZORDERINFO* zi)
 {
-    pthread_mutex_lock(&((ZORDERINFO*)zi)->rwlock);
+    pthread_mutex_lock(&zi->mutex);
 }
 
-static inline void unlock_zi_for_change (const ZORDERINFO* zi)
+static inline void unlock_zi_for_change (ZORDERINFO* zi)
 {
-    pthread_mutex_unlock(&((ZORDERINFO*)zi)->rwlock);
+    pthread_mutex_unlock(&zi->mutex);
 }
 
-static inline void lock_zi_for_read (const ZORDERINFO* zi)
+static inline void lock_zi_for_read (ZORDERINFO* zi)
 {
-    pthread_mutex_lock(&((ZORDERINFO*)zi)->rwlock);
+    pthread_mutex_lock(&zi->mutex);
 }
 
-static inline void unlock_zi_for_read (const ZORDERINFO* zi)
+static inline void unlock_zi_for_read (ZORDERINFO* zi)
 {
-    pthread_mutex_unlock(&((ZORDERINFO*)zi)->rwlock);
+    pthread_mutex_unlock(&zi->mutex);
 }
-#endif /* __NOUNIX__ */
+# endif /* notdef __ZI_USE_RWLOCK */
 
 #elif defined(_MGRM_STANDALONE)
-static inline void lock_zi_for_change (const ZORDERINFO* zi) { }
-static inline void unlock_zi_for_change (const ZORDERINFO* zi) { }
-static inline void lock_zi_for_read (const ZORDERINFO* zi) { }
-static inline void unlock_zi_for_read (const ZORDERINFO* zi) { }
+static inline void lock_zi_for_change (ZORDERINFO* zi) { }
+static inline void unlock_zi_for_change (ZORDERINFO* zi) { }
+static inline void lock_zi_for_read (ZORDERINFO* zi) { }
+static inline void unlock_zi_for_read (ZORDERINFO* zi) { }
 #else /* for procs */
 /* NULL. see desktop-procs.c */
 #endif /* _MGRM_THREADS */
diff --git a/src/kernel/zorder.c b/src/kernel/zorder.c
index 5f2eaff4..dbf9607d 100644
--- a/src/kernel/zorder.c
+++ b/src/kernel/zorder.c
@@ -243,11 +243,22 @@ int __kernel_alloc_z_order_info (int nr_topmosts, int nr_normals, BOOL with_mask
 #endif  /* deprecated code */
 
 #ifdef _MGRM_THREADS
-#ifndef __NOUNIX__
+# ifdef __ZI_USE_RWLOCK
     pthread_rwlock_init(&__mg_zorder_info->rwlock, NULL);
-#else
-    pthread_mutex_init(&__mg_zorder_info->rwlock, NULL);
-#endif
+# else
+    do {
+        int ret;
+        pthread_mutexattr_t my_attr;
+        ret = pthread_mutexattr_init(&my_attr);
+        assert(ret == 0);
+        ret = pthread_mutexattr_settype(&my_attr, PTHREAD_MUTEX_RECURSIVE);
+        assert(ret == 0);
+        pthread_mutex_init(&__mg_zorder_info->mutex, &my_attr);
+        ret = pthread_mutexattr_destroy(&my_attr);
+        assert(ret == 0);
+        (void)ret;
+    } while (0);
+#  endif
 #endif
     return 0;
 #endif
@@ -261,11 +272,11 @@ void __kernel_free_z_order_info (ZORDERINFO* zi)
 #else
 
 #ifdef _MGRM_THREADS
-#ifndef __NOUNIX__
+# ifdef __ZI_USE_RWLOCK
     pthread_rwlock_destroy(&zi->rwlock);
-#else
-    pthread_mutex_destroy(&zi->rwlock);
-#endif
+# else
+    pthread_mutex_destroy(&zi->mutex);
+# endif
 #endif
     free (zi);
     __mg_zorder_info = NULL;