EM_UNDO
wParam = 0; /* not used, must be zero */
lParam = 0L; /* not used, must be zero */An application sends an EM_UNDO message to undo the last edit-control operation.
This message has no parameters.
The return value is always nonzero for a single-line edit control. For a multiline edit control, the return value is nonzero if the undo operation is successful or zero if the undo operation fails.
An undo operation can also be undone. For example, you can restore deleted text with the first EM_UNDO message and remove the text again with a second EM_UNDO message as long as there is no intervening edit-control operation.
This example undoes the last edit-control operation:
SendDlgItemMessage(hdlg, ID_MYEDITCONTROL, EM_UNDO, 0, 0L);