Ocultar Selection-Screens

Más de una vez (Yo incluído), me ha preguntado como hacer para ocultar o mostrar un Selection-Screen...Tal como hacen algunas transacciones de SAP...La respuesta es más sencilla de lo que parece -;)

**************************************************************
* Programa: ZDUMMY_TEST.                                     *
* Consultor ABAP: Alvaro Tejada Galindo                      *
**************************************************************
REPORT ZPRUEBA_ATG.

DATA: FLAG TYPE C VALUE 'X',
      COUNTER TYPE I.

SELECTION-SCREEN BEGIN OF BLOCK B1.
SELECTION-SCREEN PUSHBUTTON 1(10) BUTTON USER-COMMAND GOCFG.
SELECTION-SCREEN END OF BLOCK B1.

SELECTION-SCREEN BEGIN OF BLOCK B2 WITH FRAME TITLE TEXT-T01.
PARAMETERS:
           CARRID TYPE SPFLI-CARRID MODIF ID SC1,
           CONNID TYPE SPFLI-CONNID MODIF ID SC1,
           CITYFROM TYPE SPFLI-CITYFROM MODIF ID SC1.
SELECTION-SCREEN END OF BLOCK B2.

*&-----------------------------------------------------------&*
*&      START-OF-SELECTION                                   &*
*&-----------------------------------------------------------&*
START-OF-SELECTION.

AT SELECTION-SCREEN OUTPUT.

  LOOP AT SCREEN.
    IF SCREEN-GROUP1 = 'SC1' AND FLAG EQ 'X'.
      COUNTER = COUNTER + 1.
      WRITE 'Ocultar' TO BUTTON.
      SCREEN-ACTIVE = '1'.
      MODIFY SCREEN.
      IF COUNTER EQ 6.
        CLEAR COUNTER.
        FLAG = SPACE.
      ENDIF.
      CONTINUE.
    ELSEIF SCREEN-GROUP1 = 'SC1' AND FLAG EQ SPACE.
      COUNTER = COUNTER + 1.
      WRITE 'Mostrar' TO BUTTON.
      SCREEN-ACTIVE = '0'.
      MODIFY SCREEN.
      IF COUNTER EQ 6.
        CLEAR COUNTER.
        FLAG = 'X'.
      ENDIF.
      CONTINUE.
    ENDIF.
  ENDLOOP.

Saludos,

Blag.