The EM_STREAMIN message replaces the contents of a rich edit control with the specified data stream.
EM_STREAMIN wParam = (WPARAM) (UINT) uFormat; lParam = (LPARAM) (EDITSTREAM FAR *) lpStream;
| Value | Meaning | 
| SF_TEXT | Text | 
| SF_RTF | Rich Text Format (RTF) | 
Both data formats may be combined with the SFF_SELECTION flag. If the SFF_SELECTION flag is specified, the stream replaces the contents of the current selection. Otherwise, the stream replaces the entire contents of the control.
The SF_RTF format may be combined with the SFF_PLAINRTF flag. If the
SFF_PLAINRTF flag is specified, language-specific RTF keywords in the stream
are ignored. Only keywords common to all languages are streamed in.
Returns the number of characters read.