这样就可以了
procedure TForm1.RichEdit1MouseWheelDown(Sender: TObject;
Shift: TShiftState; MousePos: TPoint; var Handled: Boolean);
begin
SendMessage(RichEdit1.Handle,wm_vscroll,SB_LINEDOWN,0);
end;
procedure TForm1.RichEdit1MouseWheelUp(Sender: TObject; Shift: TShiftState;
MousePos: TPoint; var Handled: Boolean);
begin
SendMessage(RichEdit1.Handle,wm_vscroll,SB_LINEUP,0);
end;
