This is wmpuzzle, written by Martin A. Godisch <martin@godisch.de>. The
source code can be found at http://www.godisch.de/debian/wmpuzzle/.

Copyright (c) 2002-2006 Martin A. Godisch <martin@godisch.de>.

  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License along
  with this program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

On Debian GNU/Linux systems, the complete text of the GNU General Public
License can be found in '/usr/share/common-licenses/GPL'.