SET (INPUT_FOCUS)

  Causes TPU to request the input focus.

  Syntax

     SET (INPUT_FOCUS [, SCREEN | widget])

  Parameters

     SCREEN               A keyword indicating that the top-level widget
                          associated with TPU is to receive the input
                          focus.  The default if not specified.

     widget               The widget that is to receive the input focus.  If
                          you do not specify this second parameter, TPU
                          requests input focus for the top-level widget.