tune description of MSG_CHAR

RELEASE-NOTES.md

@@ -104,7 +104,7 @@ The main changes in structure and functions:
 
 ##### Message
 
-As a result, the strcuture `MSG` and all message-related functions changed.
+The strcuture `MSG` and all message-related functions changed.
 For example, the prototype of `SendMessage` changed from
 
     int SendMessage (HWND hWnd, int nMsg, WPARAM wParam, LPARAM lParam)
@@ -113,6 +113,19 @@ to
 
     LRESULT SendMessage (HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam)
 
+_IMPORTANT NOTE_
+
+For best portability, you should use `LOBYTE_WORD16` and `HIBYTE_WORD16`
+to get the bytes of a character when you extract the bytes from `WPARAM` 
+parameter of a `MSG_CHAR` message:
+
+    MSG_CHAR
+    WORD16 ch = (WORD16)wParam;
+    DWORD key_flags = (DWORD)lParam;
+    byte0 = LOBYTE_WORD16 (ch);
+    byte1 = HIBYTE_WORD16 (ch);
+
+
 ##### Window callback procedure 
 
 Furthermore, the structure and functions to register window class, 

include/window.h

@@ -420,11 +420,11 @@ extern "C" {
  *
  * \code
  * MSG_CHAR
- * int ch = (int)wParam;
+ * WORD16 ch = (WORD16)wParam;
  * DWORD key_flags = (DWORD)lParam;
  * \endcode
  *
- * \param ch The ASCII code of the pressed key.
+ * \param ch The EUC code of the pressed key.
  * \param key_flags The shift key status when this message occurred.
  *
  * \note Please use \a LOBYTE_WORD16 and \a HIBYTE_WORD16 to get the bytes