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