How to hide certain fields or button in your selection screen

*&---------------------------------------------------------------------*
*& Report Y_MARK
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REPORT Y_MARK.


DATA: D_UCOMM LIKE SY-UCOMM.

PARAMETERS: P_GRPA1(10) MODIF ID A,
P_GRPA2(5) MODIF ID A,
P_GRPB1(2) MODIF ID B.

PARAMETERS: P_ACTA RADIOBUTTON GROUP RAD1 USER-COMMAND ACT DEFAULT 'X',
P_ACTB RADIOBUTTON GROUP RAD1.

AT SELECTION-SCREEN.
D_UCOMM = SY-UCOMM.

AT SELECTION-SCREEN OUTPUT.
LOOP AT SCREEN.
IF P_ACTA = 'X'.
IF SCREEN-GROUP1 = 'B'.
SCREEN-ACTIVE = 0.
ENDIF.
ELSEIF P_ACTB = 'X'.
IF SCREEN-GROUP1 = 'A'.
SCREEN-ACTIVE = 0.
ENDIF.
ENDIF.
MODIFY SCREEN.
ENDLOOP.

START-OF-SELECTION.