An application sends an EM_CANUNDO message to determine whether an
edit-control operation can be undone; that is, whether the control can respond to the
EM_UNDO message.
EM_CANUNDO
wParam = 0; // not used; must be zero
lParam = 0; // not used; must be zero
Parameters
This message has no parameters.
Return Values
If the edit control can correctly process the EM_UNDO message, the return
value is TRUE; otherwise, it is FALSE.
See Also
EM_UNDO