[API]关于代替RichTextBox控件的selStart属性的API函数不支持分析双字节的问题,静侯高手解答！

本人在用VB6开发文本编辑器时，为了顾全功能，使用了RichTextBox控件

但开发末期发现其selstart、sellength两个属性的使用效率“极差”！当编辑器有50000-100000字符时，如果光标靠文档末尾在使用selstart、sellength这两个属性巨慢+巨占用CPU

上次经过“rainstormmaster(暴风雨 v2.0)”的解答后，得知用以下API代码可以取代selstart属性，获得当前光标前有多少字符（光标位于第几个字符）

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Const WM_USER As Long = &H400
Private Const EM_EXGETSEL As Long = (WM_USER + 52)
Private Const EM_EXSETSEL As Long = (WM_USER + 55)
Private Const EM_GETSELTEXT As Long = (WM_USER + 62)
Private Const EM_GETSEL As Long = &HB0
Private Const EM_SETSEL As Long = &HB1
Private Type Range
cpMin As Long
cpMax As Long
End Type

Private Sub Command1_Click()
Dim cr As Range
Call SendMessage(RichTextBox1.hwnd, EM_EXGETSEL, 0, cr)
Dim start As Long, ende As Long, length As Long
start=cr.cpMin
msgbox "当前光标位于" & start
End Sub

但我发现，得到的这个数字是区分“中文或他国双字节符号、标准英文键盘符号”的，也就是说一个中文它会以为是2个字，这使我大伤脑筋，做了1个星期的测试也没能得到真实的光标位置，我想到了用strconv等转换但还是不行

只好在次请教大家了，如何用新方法或改编“rainstormmaster(暴风雨 v2.0)”的方法实现得到当前光标的真实位置？（不区分中英文）