The EN_MSGFILTER notification message notifies a rich edit control’s parent window of a keyboard or mouse event in the control. A rich edit control sends this notification message in the form of a WM_NOTIFY message.
EN_MSGFILTER wParam = (WPARAM) (UINT) uID; lParam = (LPARAM) (MSGFILTER) lpMsgFilter;
Returns a nonzero value if the control should process the event, or zero if the control should ignore the event.