Added some STN_xxx macros.

diff --git a/include/winuser.h b/include/winuser.h
index 85a9023..82a9449 100644
--- a/include/winuser.h
+++ b/include/winuser.h
@@ -1655,6 +1655,12 @@
 #define STM_GETICON       0x0171
 #define STM_SETIMAGE        0x0172
 #define STM_GETIMAGE        0x0173
+#define STM_MSGMAX          0x0174
+
+#define STN_CLICKED         0
+#define STN_DBLCLK          1
+#define STN_ENABLE          2
+#define STN_DISABLE         3
 
 /* Scrollbar messages */
 #define SBM_SETPOS             0x00e0