This message directs a multiline edit control to add or remove the end-of-line character from word wrapped text lines.
wParam
Indicates the disposition of end-of-line characters. If the wParam parameter is nonzero, the characters CR CR LF (0D 0D 0A hexadecimal) are placed at the end of wordwrapped lines. If wParam is zero, the end-of-line characters are removed from the text.
lParam
This parameter is not used.
The return value is nonzero if any formatting occurs. Otherwise, it is zero.
Lines that end with a hard return (a carriage return entered by the user) contain the characters CR LF at the end of the line. These lines are not affected by the EM_FMTLINES message.
Notice that the size of the text changes when this message is processed.