wdm copyright

["Marcelo E. Magallon" <mmagallo@efis.ucr.ac.cr>]

Hi,

 recently someone announced a new xdm-alike application: wdm (WINGs
 Display Manager). It's GPLed. But it's based on XDM (based = most of
 the code is xdm actually and you need xdm's source to build
 this). The X Consortium copyright appears on xdm's source, so I
 presume this license applies to it:

   Permission is hereby granted, free of charge, to any person
   obtaining a copy of this software and associated documentation
   files (the "Software"), to deal in the Software without
   restriction, including without limitation the rights to use, copy,
   modify, merge, publish, distribute, sublicense, andør sell copies
   of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.
 
 Now my question is: is it ok to release this thing under the GPL?
 Moving from the X Consortium's license to GPL is a rather drastic
 license change. Should the copyright read something more like xbase's
 copyright, i.e., the part the wdm author wrote is GPLed, and the xdm
 stuff is still under X Consortium's license or XFree86's?


                                        Marcelo