SET (INPUT_FOCUS_GRAB)

  Specifies the program or learn sequence DECTPU should execute whenever it
  processes a FocusIn event from DECwindows.

  Syntax

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

  Parameters

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

     program_source       A string, buffer, range, learn sequence, or
                          program specifying the input focus routine.  If
                          you do not specify this parameter, DECTPU deletes
                          the current input focus routine; thereafter, your
                          application is not informed when DECTPU processes
                          a FocusIn event from DECwindows.

     NONE                 A keyword instructing DECTPU to delete the current
                          input focus routine.