Dynamically show/hide selection screen elements

TABLES: mara.

PARAMETERS: p_901 RADIOBUTTON GROUP rad1 DEFAULT 'X' USER-COMMAND usr,
            p_948 RADIOBUTTON GROUP rad1.

SELECTION-SCREEN BEGIN OF BLOCK b1 WITH FRAME TITLE text-001.
SELECT-OPTIONS : s_matnr FOR mara-matnr MODIF ID m1,
                 s_maktl FOR mara-matkl MODIF ID m2.
SELECTION-SCREEN: END OF BLOCK b1.

AT SELECTION-SCREEN OUTPUT.
  LOOP AT SCREEN.
    IF p_901 = 'X'.
      IF screen-group1 = 'M2'.
        screen-active = 0.
      ENDIF.
      MODIFY SCREEN.
    ELSEIF p_948 = 'X'.
      IF screen-group1 = 'M1'.
        screen-active = 0.
      ENDIF.
      MODIFY SCREEN.
    ENDIF.
  ENDLOOP.