Hiding/Unhiding selection screen

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*& Report Z_HRA
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*&
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REPORT Z_HRA.

tables: pa0000, pa0001.

parameters: p_chk1 as checkbox user-command rusr,
p_chk2 as checkbox user-command rusr,
p_chk3 as checkbox user-command rusr,
p_chk4 as checkbox user-command rusr,
p_chk5 as checkbox user-command rusr.

selection-screen: begin of block blk1 with frame.
select-options: s_pernr for pa0000-pernr modif id ABC no-extension no intervals,
s_stat2 for pa0000-stat2 modif id DEF,
s_werks for pa0001-werks modif id GHI,
s_persg for pa0001-persg modif id JKL,
s_persk for pa0001-persk modif id MNO.
selection-screen: end of block blk1.

AT SELECTION-SCREEN output.

LOOP AT SCREEN.

IF SCREEN-GROUP1 = 'ABC'.
IF p_chk1 = 'X'.
SCREEN-ACTIVE = 1.
ELSE.
SCREEN-ACTIVE = 0.
ENDIF.
MODIFY SCREEN.
ENDIF.

IF SCREEN-GROUP1 = 'DEF'.
IF p_chk2 = 'X'.
SCREEN-ACTIVE = 1.
ELSE.
SCREEN-ACTIVE = 0.
ENDIF.
MODIFY SCREEN.
ENDIF.

IF SCREEN-GROUP1 = 'GHI'.
IF p_chk3 = 'X'.
SCREEN-ACTIVE = 1.
ELSE.
SCREEN-ACTIVE = 0.
ENDIF.
MODIFY SCREEN.
ENDIF.

IF SCREEN-GROUP1 = 'JKL'.
IF p_chk4 = 'X'.
SCREEN-ACTIVE = 1.
ELSE.
SCREEN-ACTIVE = 0.
ENDIF.
MODIFY SCREEN.
ENDIF.

IF SCREEN-GROUP1 = 'MNO'.
IF p_chk5 = 'X'.
SCREEN-ACTIVE = 1.
ELSE.
SCREEN-ACTIVE = 0.
ENDIF.
MODIFY SCREEN.
ENDIF.

ENDLOOP.

*Titles for check boxes and select options

*P_CHK1 Personal Number
*P_CHK2 Employment Status
*P_CHK3 Personnel Area
*P_CHK4 Employee Group
*P_CHK5 Employee Sub group
*S_PERNR Personal Number
*S_PERSG Employee Group
*S_PERSK Employee Sub group
*S_STAT2 Employment Status
*S_WERKS Personnel Area