SET (GLOBAL_SELECT_UNGRAB)

  Specifies the program or learn sequence TPU should execute whenever it
  loses ownership of a global selection.

  Syntax

     SET (GLOBAL_SELECT_UNGRAB, SCREEN [, {program_source | NONE}])

  Parameters

     SCREEN               A keyword used for compatibility with future
                          versions of TPU.

     program_source       A string, buffer, range, learn sequence, or
                          program specifying the ungrab procedure.  If you
                          do not specify this parameter, TPU deletes the
                          current global selection ungrab routine;
                          thereafter, your application is not informed when
                          TPU loses ownership of a global selection.

     NONE                 A keyword instructing TPU to delete the current
                          global selection ungrab routine.