private void KeyUp(object sender, KeyEventArgs kea)
        {
            if (_keys.Contains((int) kea.KeyCode))
                _keys.Remove((int) kea.KeyCode);

            if (!_keysUp.Contains((int) kea.KeyCode))
                _keysUp.Add((int) kea.KeyCode);
        }
        private void KeyDown(object sender, KeyEventArgs kea)
        {
            if (!_keys.Contains((int) kea.KeyCode))
            {
                _keys.Add((int) kea.KeyCode);

                if (!_keysDown.Contains((int) kea.KeyCode))
                    _keysDown.Add((int) kea.KeyCode);
            }
        }