PARAMETERS show_all AS CHECKBOX USER-COMMAND flag.

SELECTION-SCREEN BEGIN OF BLOCK b1 WITH FRAME.
PARAMETERS: p1 TYPE c LENGTH 10,
            p2 TYPE c LENGTH 10,
            p3 TYPE c LENGTH 10.
SELECTION-SCREEN END OF BLOCK b1.

SELECTION-SCREEN BEGIN OF BLOCK b2 WITH FRAME.
PARAMETERS: p4 TYPE c LENGTH 10 MODIF ID bl2,
            p5 TYPE c LENGTH 10 MODIF ID bl2,
            p6 TYPE c LENGTH 10 MODIF ID bl2.
SELECTION-SCREEN END OF BLOCK b2.

AT SELECTION-SCREEN OUTPUT.
  LOOP AT SCREEN.
    IF show_all <> 'X' AND
       screen-group1 = 'BL2'.
       screen-active = '0'.
    ENDIF.
    MODIFY SCREEN.
  ENDLOOP.