RichEdit 1.0不支持unicode方式，以unicode方式使用的话在计算字符长度时会出错。
系统支持版本
Windows XP SP1
Includes Rich Edit 4.1, Rich Edit 3.0, and a Rich Edit 1.0 emulator.
Windows XP
Includes Rich Edit 3.0 with a Rich Edit 1.0 emulator.
Windows Me
Includes Rich Edit 1.0 and 3.0.
Windows 2000
Includes Rich Edit 3.0 with a Rich Edit 1.0 emulator.
Windows NT 4.0
Includes Rich Edit 1.0 and 2.0.
Windows 98
Includes Rich Edit 1.0 and 2.0.
Windows 95
Includes only Rich Edit 1.0. However, Riched20.dll is compatible with Windows 95 and may be installed by an application that requires it.
MSDN
ms-help://MS.VSCC.2003/MS.MSDNQTR.2004JAN.1033/shellcc/platform/commctls/richedit/richeditcontrols/aboutricheditcontrols.htm
通过#include <Richedit.h>前定义
#define _RICHEDIT_VER 0x0300
定义使用控件的版本
