diff --git a/configure.ac b/configure.ac
index 7dccda53..6e0796da 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1696,8 +1696,6 @@ if test "x$devel_mode" = "xyes"; then
     enable_video_custom="yes"
 
     build_screensaver="yes"
-
-    CFLAGS="$CFLAGS -Werror"
 fi
 
 dnl Depedencies
@@ -2433,11 +2431,17 @@ fi
 dnl ========================================================================
 dnl Write output
 
-# define _GNU_SOURCE for pthread_rwlock_t
+dnl define _GNU_SOURCE for pthread_rwlock_t
 CFLAGS="$CFLAGS -D_GNU_SOURCE"
 
+if test "x$devel_mode" = "xyes"; then
+    if test "$ac_cv_prog_gcc" = "yes"; then
+        CPPFLAGS="$CPPFLAGS -Wall -Werror"
+    fi
+fi
+
 if test "$ac_cv_prog_gcc" = "yes"; then
-    CFLAGS="$CFLAGS -Wall -Wstrict-prototypes -pipe"
+    CFLAGS="$CFLAGS -Wstrict-prototypes -pipe"
 fi
 
 if test "x$runtime_mode" = "xths"; then
diff --git a/include/common.h b/include/common.h
index 86848eec..85625ce4 100644
--- a/include/common.h
+++ b/include/common.h
@@ -299,22 +299,22 @@ typedef int BOOL;
 #   endif
 #endif
 
+/**
+ * \def INV_PTR
+ * \brief A value indicates an invalid non-null pointer.
+ */
+#define INV_PTR                ((void *)-1)
+
 #define GUIAPI
 
 #if !defined(__NODLL__) && (defined (WIN32) || defined (__NUCLEUS_MNT__))
-  #if defined(__MINIGUI_LIB__) && !defined(__MGEXT_LIB__)
-  #define MG_EXPORT       __declspec(dllexport)
-  #else
-  #define MG_EXPORT       __declspec(dllimport) 
-  #endif
-  #if defined(__MGEXT_LIB__)
-  #define MGEXT_EXPORT    __declspec(dllexport)
-  #else
-  #define MGEXT_EXPORT    __declspec(dllimport) 
-  #endif
+#   if defined(__MINIGUI_LIB__)
+#       define MG_EXPORT       __declspec(dllexport)
+#   else
+#       define MG_EXPORT       __declspec(dllimport) 
+#   endif
 #else
-  #define MG_EXPORT
-  #define MGEXT_EXPORT
+#   define MG_EXPORT
 #endif
 
     /** @} end of simple_types */
@@ -499,6 +499,12 @@ typedef long LONG_PTR;
 typedef int LONG_PTR;
 #endif
 
+/**
+ * \var LINT
+ * \brief Signed integer which has pointer precision.
+ */
+typedef LONG_PTR LINT;
+
 /**
  * \var LRESULT
  * \brief Signed result of message processing.
diff --git a/include/gdi.h b/include/gdi.h
index d916b787..7261bc6d 100644
--- a/include/gdi.h
+++ b/include/gdi.h
@@ -1090,19 +1090,19 @@ MG_EXPORT BOOL GUIAPI InitPolygonRegion (PCLIPRGN dst,
  * \note MiniGUI does not do any clipping operation for this DC, 
  *       so use this DC may make a mess of other windows. 
  */
-#define HDC_SCREEN          (HDC)0
+#define HDC_SCREEN          ((HDC)0)
 
 /* 
  * This is a system screen DC create for MiniGUI internal usage, for example,
  * menu and z-order operations
  */
-#define HDC_SCREEN_SYS      (HDC)1
+#define HDC_SCREEN_SYS      ((HDC)1)
 
 /**
  * \def HDC_INVALID
  * \brief Indicates an invalid handle to device context.
  */
-#define HDC_INVALID         (HDC)-1
+#define HDC_INVALID         ((HDC)-1)
 
 #define GDCAP_COLORNUM      0
 #define GDCAP_HPIXEL        1
diff --git a/include/window.h b/include/window.h
index b9694e83..7d9a51a3 100644
--- a/include/window.h
+++ b/include/window.h
@@ -2173,7 +2173,7 @@ typedef struct _MSG
     /** The second parameter of the message (32-bit integer). */
     LPARAM          lParam;
     /** Time */
-    ULONG           time;
+    DWORD           time;
 #ifdef _MGRM_THREADS
     /** Addtional data*/
     void*            pAdd;
@@ -4893,15 +4893,15 @@ extern MG_EXPORT HWND __mg_hwnd_desktop;
  * \def HWND_NULL
  * \brief Null window handle.
  */
-#define HWND_NULL           (HWND)0
+#define HWND_NULL           ((HWND)0)
 
 /**
  * \def HWND_INVALID
  * \brief Invalid window handle.
  */
-#define HWND_INVALID        (HWND)-1
+#define HWND_INVALID        ((HWND)-1)
 
-#define HWND_OTHERPROC      (HWND)-1
+#define HWND_OTHERPROC      ((HWND)-1)
 
 /**
  * Structure defines a main window.
@@ -7544,7 +7544,7 @@ MG_EXPORT NOTIFPROC GUIAPI GetNotificationCallback (HWND hwnd);
      */
 
 /**
- * \var typedef BOOL (* TIMERPROC)(HWND, int, DWORD)
+ * \var typedef BOOL (* TIMERPROC)(HWND, LINT, DWORD)
  * \brief Type of the timer callback procedure.
  *
  * This is the prototype of the callback procedure of a timer created by SetTimerEx.
@@ -7554,11 +7554,14 @@ MG_EXPORT NOTIFPROC GUIAPI GetNotificationCallback (HWND hwnd);
  * by MiniGUI automatically. This can be used to implement a one-shot timer.
  *
  * \sa SetTimerEx
+ *
+ * \note The prototype had changed since MiniGUI v3.2; the old one:
+ *      BOOL (* TIMERPROC)(HWND, int, unsigned int)
  */
-typedef BOOL (* TIMERPROC)(HWND, int, DWORD);
+typedef BOOL (* TIMERPROC)(HWND, LINT, DWORD);
 
 /**
- * \fn BOOL GUIAPI SetTimerEx (HWND hWnd, int id, unsigned int speed, \
+ * \fn BOOL GUIAPI SetTimerEx (HWND hWnd, LINT id, DWORD speed, \
  *              TIMERPROC timer_proc)
  * \brief Creates a timer with the specified timeout value.
  *
@@ -7586,11 +7589,14 @@ typedef BOOL (* TIMERPROC)(HWND, int, DWORD);
  * \note You should set, reset, and kill a timer in the same thread if your
  *       MiniGUI is configured as MiniGUI-Threads.
  *
+ * \note The prototype had changed since MiniGUI v3.2; the old one:
+ *      BOOL GUIAPI SetTimerEx (HWND hWnd, int id, unsigned int speed, TIMERPROC timer_proc);
+ *
  * Example:
  *
  * \include settimer.c
  */
-MG_EXPORT BOOL GUIAPI SetTimerEx (HWND hWnd, int id, unsigned int speed, 
+MG_EXPORT BOOL GUIAPI SetTimerEx (HWND hWnd, LINT id, DWORD speed, 
                 TIMERPROC timer_proc);
 
 /**
@@ -7603,23 +7609,26 @@ MG_EXPORT BOOL GUIAPI SetTimerEx (HWND hWnd, int id, unsigned int speed,
                 SetTimerEx(hwnd, id, speed, NULL)
 
 /**
- * \fn int GUIAPI KillTimer (HWND hWnd, int id)
+ * \fn int GUIAPI KillTimer (HWND hWnd, LINT id)
  * \brief Destroys a timer.
  *
  * This function destroys the specified timer \a id.
  *
  * \param hWnd The window owns the timer.
- * \param id The identifier of the timer. If \a id equals or is less than 0, 
+ * \param id The identifier of the timer. If \a id equals 0, 
  *        this function will kill all timers in the system.
  *
  * \return The number of actually killed timer.
  *
  * \sa SetTimer
+ *
+ * \note The prototype had changed since MiniGUI v3.2; the old one:
+ *      int GUIAPI KillTimer (HWND hWnd, int id)
  */
-MG_EXPORT int GUIAPI KillTimer (HWND hWnd, int id);
+MG_EXPORT int GUIAPI KillTimer (HWND hWnd, LINT id);
 
 /**
- * \fn BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed, \
+ * \fn BOOL GUIAPI ResetTimerEx (HWND hWnd, LINT id, DWORD speed, \
  *              TIMERPROC timer_proc)
  * \brief Adjusts a timer with a different timeout value or different
  *        timer callback procedure.
@@ -7630,14 +7639,17 @@ MG_EXPORT int GUIAPI KillTimer (HWND hWnd, int id);
  * \param id The identifier of the timer.
  * \param speed The new timeout value.
  * \param timer_proc The new timer callback procedure. If \a timer_proc
- *        is 0xFFFFFFFF, the setting of timer callback procedure will
- *        not changed.
+ *        is INV_PTR, the setting of timer callback procedure will
+ *        not change.
  *
  * \return TRUE on success, FALSE on error.
  *
  * \sa SetTimerEx
+ *
+ * \note The prototype had changed since MiniGUI v3.2; the old one:
+ *      BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed, TIMERPROC timer_proc)
  */
-MG_EXPORT BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed,
+MG_EXPORT BOOL GUIAPI ResetTimerEx (HWND hWnd, LINT id, DWORD speed,
                 TIMERPROC timer_proc);
 
 /**
@@ -7647,10 +7659,10 @@ MG_EXPORT BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed,
  * \sa ResetTimerEx
  */
 #define ResetTimer(hwnd, id, speed) \
-                ResetTimerEx(hwnd, id, speed, (TIMERPROC)0xFFFFFFFF)
+                ResetTimerEx(hwnd, id, speed, (TIMERPROC)INV_PTR)
 
 /**
- * \fn unsigned int GUIAPI GetTickCount (void)
+ * \fn DWORD GUIAPI GetTickCount (void)
  * \brief Retrieves the tick counts that have elapsed since MiniGUI was started.
  *
  * This function retrieves the tick counts that have elapsed since MiniGUI 
@@ -7658,11 +7670,14 @@ MG_EXPORT BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed,
  * for a general Linux box, the returned tick count value is in unit of 10ms.
  *
  * \return The tick counts value that have elapsed since MiniGUI was started.
+ *
+ * \note The prototype had changed since MiniGUI v3.2; The old one:
+ *      unsinged int GUIAPI GetTickCount (void);
  */
-MG_EXPORT unsigned int GUIAPI GetTickCount (void);
+MG_EXPORT DWORD GUIAPI GetTickCount (void);
 
 /**
- * \fn BOOL GUIAPI IsTimerInstalled (HWND hWnd, int id)
+ * \fn BOOL GUIAPI IsTimerInstalled (HWND hWnd, LINT id)
  * \brief Determines whether a timer is installed.
  *
  * This function determines whether a timer with identifier \a id of 
@@ -7674,8 +7689,11 @@ MG_EXPORT unsigned int GUIAPI GetTickCount (void);
  * \return TRUE for installed, otherwise FALSE. 
  *
  * \sa SetTimer, HaveFreeTimer
+ *
+ * \note The prototype had changed since MiniGUI v3.2; the old one:
+ *      BOOL GUIAPI IsTimerInstalled (HWND hWnd, int id)
  */
-MG_EXPORT BOOL GUIAPI IsTimerInstalled (HWND hWnd, int id);
+MG_EXPORT BOOL GUIAPI IsTimerInstalled (HWND hWnd, LINT id);
 
 /**
  * \fn BOOL GUIAPI HaveFreeTimer (void)
diff --git a/src/client/client.c b/src/client/client.c
index b28d0af3..e1b31587 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -235,8 +235,8 @@ static void check_live (void)
 
 BOOL client_IdleHandler4Client (PMSGQUEUE msg_que)
 {
-    static unsigned int old_timer;
-    static int repeat_timeout = TIMEOUT_START_REPEAT;
+    static DWORD old_timer;
+    static long repeat_timeout = TIMEOUT_START_REPEAT;
     fd_set rset, wset, eset;
     fd_set* wsetptr = NULL;
     fd_set* esetptr = NULL;
diff --git a/src/include/internals.h b/src/include/internals.h
index 0be8e69a..67d8331e 100644
--- a/src/include/internals.h
+++ b/src/include/internals.h
@@ -35,7 +35,7 @@ void screensaver_hide(void);
  */
 #define WS_EX_CTRLASMAINWIN     0x20000000L
 
-#define DEF_NR_TIMERS       32
+#define DEF_NR_TIMERS           NR_BITS_DWORD
 
 #if defined (__NOUNIX__) || defined (__uClinux__)
   #define DEF_MSGQUEUE_LEN    16
@@ -475,7 +475,7 @@ PGCRINFO kernel_GetGCRgnInfo (HWND hWnd);
 /* internal variables */
 typedef struct _TRACKMENUINFO* PTRACKMENUINFO;
 
-extern unsigned int __mg_timer_counter;
+extern DWORD __mg_timer_counter;
 
 extern HWND __mg_capture_wnd;
 extern HWND __mg_ime_wnd;
diff --git a/src/include/sharedres.h b/src/include/sharedres.h
index 5978a3be..b2ec4290 100644
--- a/src/include/sharedres.h
+++ b/src/include/sharedres.h
@@ -43,8 +43,8 @@ typedef struct tagG_RES {
 
     GHANDLE topmost_layer;
 
-    unsigned int timer_counter;
-    unsigned int tick_on_locksem;
+    DWORD timer_counter;
+    DWORD tick_on_locksem;
     struct timeval timeout;
     struct termios savedtermio;
 #ifdef _MGRM_PROCESSES
diff --git a/src/include/timer.h b/src/include/timer.h
index dfdd0d24..020df95c 100644
--- a/src/include/timer.h
+++ b/src/include/timer.h
@@ -20,14 +20,14 @@ extern "C" {
 #define USEC_10MS       10000
 
 typedef struct _timer {
-    HWND    hWnd;
-    int     id;
-    unsigned int speed;
-    unsigned int count;
+    HWND        hWnd;
+    LINT        id;
+    DWORD       speed;
+    UINT_PTR    count;
 
-    TIMERPROC proc;
-    unsigned int tick_count;
-    PMSGQUEUE msg_queue;
+    TIMERPROC   proc;
+    UINT_PTR    tick_count;
+    PMSGQUEUE   msg_queue;
 } TIMER;
 typedef TIMER* PTIMER;
 
diff --git a/src/kernel/timer.c b/src/kernel/timer.c
index 4875127c..9a3d02b2 100644
--- a/src/kernel/timer.c
+++ b/src/kernel/timer.c
@@ -3,7 +3,7 @@
 **
 ** timer.c: The Timer module for MiniGUI-Threads.
 **
-** Copyright (C) 2003 ~ 2008 Feynman Software.
+** Copyright (C) 2003 ~ 2018 Feynman Software.
 ** Copyright (C) 1999 ~ 2002 Wei Yongming.
 **
 ** All rights reserved by Feynman Software.
@@ -39,7 +39,7 @@
 #define TIMER_ERR_SYS(text)
 #endif
 
-unsigned int __mg_timer_counter = 0;
+DWORD __mg_timer_counter = 0;
 static TIMER *timerstr[DEF_NR_TIMERS];
 
 #ifdef _MGRM_THREADS
@@ -351,15 +351,17 @@ void __mg_move_timer_last (TIMER* timer, int slot)
 }
 #endif
 
-BOOL GUIAPI SetTimerEx (HWND hWnd, int id, unsigned int speed, 
+BOOL GUIAPI SetTimerEx (HWND hWnd, LINT id, DWORD speed, 
                 TIMERPROC timer_proc)
 {
     int i;
-    PMSGQUEUE pMsgQueue;
     int slot = -1;
+    PMSGQUEUE pMsgQueue;
 
-    if (speed <= 0)
-    {
+    if (id == 0)
+        return FALSE;
+
+    if (speed == 0) {
         speed = 1;
     }
 
@@ -467,8 +469,8 @@ void mg_remove_timers_by_msg_queue (const MSGQUEUE* msg_que)
     TIMER_UNLOCK ();
 }
 
-/* If id <= 0, clear all timers of the window */
-int GUIAPI KillTimer (HWND hWnd, int id)
+/* If id == 0, clear all timers of the window */
+int GUIAPI KillTimer (HWND hWnd, LINT id)
 {
     int i;
     PMSGQUEUE pMsgQueue;
@@ -485,13 +487,13 @@ int GUIAPI KillTimer (HWND hWnd, int id)
 
     for (i = 0; i < DEF_NR_TIMERS; i++) {
         if ((timerstr [i] && timerstr [i]->hWnd == hWnd) && 
-                        (id <= 0 || timerstr [i]->id == id)) {
+                        (id == 0 || timerstr [i]->id == id)) {
             RemoveMsgQueueTimerFlag (pMsgQueue, i);
             free (timerstr[i]);
             timerstr [i] = NULL;
             killed ++;
 
-            if (id > 0) break;
+            if (id) break;
         }
     }
 
@@ -504,12 +506,15 @@ int GUIAPI KillTimer (HWND hWnd, int id)
     return killed;
 }
 
-BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed, 
+BOOL GUIAPI ResetTimerEx (HWND hWnd, LINT id, DWORD speed, 
                 TIMERPROC timer_proc)
 {
     int i;
     PMSGQUEUE pMsgQueue;
 
+    if (id == 0)
+        return FALSE;
+
 #ifdef _MGRM_THREADS
     if (!(pMsgQueue = GetMsgQueueThisThread ()))
         return FALSE;
@@ -519,13 +524,13 @@ BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed,
 
     TIMER_LOCK ();
 
-    for (i=0; i<DEF_NR_TIMERS; i++) {
+    for (i = 0; i < DEF_NR_TIMERS; i++) {
       if (timerstr[i] && timerstr[i]->hWnd == hWnd && timerstr[i]->id == id) {
         /* Should clear old timer flags */
         RemoveMsgQueueTimerFlag (pMsgQueue, i);
         timerstr[i]->speed = speed;
         timerstr[i]->count = 0;
-        if (timer_proc != (TIMERPROC)0xFFFFFFFF)
+        if (timer_proc != (TIMERPROC)INV_PTR)
             timerstr[i]->proc = timer_proc;
         timerstr[i]->tick_count = 0;
 
@@ -538,13 +543,16 @@ BOOL GUIAPI ResetTimerEx (HWND hWnd, int id, unsigned int speed,
     return FALSE;
 }
 
-BOOL GUIAPI IsTimerInstalled (HWND hWnd, int id)
+BOOL GUIAPI IsTimerInstalled (HWND hWnd, LINT id)
 {
     int i;
 
+    if (id == 0)
+        return FALSE;
+
     TIMER_LOCK ();
 
-    for (i=0; i<DEF_NR_TIMERS; i++) {
+    for (i = 0; i < DEF_NR_TIMERS; i++) {
         if ( timerstr[i] != NULL ) {
             if ( timerstr[i]->hWnd == hWnd && timerstr[i]->id == id) {
                 TIMER_UNLOCK ();
@@ -570,7 +578,7 @@ BOOL GUIAPI HaveFreeTimer (void)
     return FALSE;
 }
 
-unsigned int GUIAPI GetTickCount (void)
+DWORD GUIAPI GetTickCount (void)
 {
 #ifdef _MGRM_PROCESSES
     return SHAREDRES_TIMER_COUNTER;
diff --git a/src/server/client.c b/src/server/client.c
index 3479d216..8fe52e8c 100644
--- a/src/server/client.c
+++ b/src/server/client.c
@@ -34,7 +34,7 @@
 
 #define    NALLOC       4        /* #Client structs to alloc/realloc for */
 
-extern unsigned int __mg_timer_counter;
+extern DWORD __mg_timer_counter;
 
 MG_Client* mgClients = NULL;
 int mgClientSize = 0;
diff --git a/src/server/server.c b/src/server/server.c
index d36e979a..198ef333 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -41,7 +41,7 @@
 #include "drawsemop.h"
 #include "license.h"
 
-extern unsigned int __mg_timer_counter;
+extern DWORD __mg_timer_counter;
 
 ON_NEW_DEL_CLIENT OnNewDelClient = NULL;
 
diff --git a/src/textedit/object.h b/src/textedit/object.h
index 2ca7322e..9b355ccb 100644
--- a/src/textedit/object.h
+++ b/src/textedit/object.h
@@ -57,7 +57,7 @@ ClassType(clss) Class(clss) = { (PClassConstructor)clss##ClassConstructor }; \
 static const char* clss##_type_name = #clss; \
 static ClassType(clss) * clss##ClassConstructor(ClassType(clss)* _class) { \
 	unsigned short * _pintfOffset = NULL; \
-	_pintfOffset = (PVOID)((UINT_PTR)_pintfOffset ^ 0); /* prevent unused-but-set-variable warning */ \
+	_pintfOffset = (PVOID)((UINT_PTR)_pintfOffset ^ 0); /* VW: prevent unused-but-set-variable warning */ \
 	_class = (ClassType(clss)*)((PClassConstructor)(Class(superCls).classConstructor))((mObjectClass*)_class); \
 	_pintfOffset = &_class->intfOffset; \
 	_class->super = &Class(superCls); \