This message is sent to the multiline edit control, informing the edit control that Windows has replaced the default word-break function with an application-supplied word-break function. A word-break function scans a text buffer (which contains text to be sent to the display), looking for the first word that will not fit on the current display line. The word-break function places this word at the beginning of the next line on the display. A word-break function defines at what point Windows should break a line of text for multiline edit controls, usually at a blank character that separates two words. The default word-break function breaks a line of text at a blank character. The application-supplied function may define a word break to be a hyphen or character other than the blank character.
The EM_SETWORDBREAK message may be used as either a wide-character message (where text arguments must use Unicode) or an ANSI message (where text arguments must use characters from the Windows 3.x character set installed).
wParam
This parameter is not used.
lParam
Is a callback address. See the description of the WordBreakProc callback function.