Call this function to replace the current selection in an edit control with the text specified by lpszNewText.
Points to a null-terminated string containing the replacement text.
To specify that this function can be undone, set the value of this parameter to TRUE . The default value is FALSE.
Replaces only a portion of the text in an edit control. If you want to replace all of the text, use the CWnd::SetWindowText member function.
If there is no current selection, the replacement text is inserted at the current cursor location.
For more information, see EM_REPLACESEL in the Platform SDK.