//Выключение курсора
procedure TForm1.Button1Click(Sender: TObject);
var
 CState: Integer;
begin
 CState := ShowCursor(True);
 while Cstate >= 0 do
  Cstate := ShowCursor(False);
end;
//Включение курсора
procedure TForm1.Button2Click(Sender: TObject);
var
 Cstate: Integer;
begin
 Cstate := ShowCursor(True);
 while CState < 0 do
  CState := ShowCursor(True);
end;