How to hide selection-screen fields dynamically

Hiding fields on selection-screen dynamically Screen 1   Screen 2     Codes:   report  zanil   . * Selection-Screen Hiding Fields Dynamically tables: mara. parameter: rb1 radiobutton group rb1            default ‘X’ user-command comm. parameter: rb2 radiobutton group rb1 . select–options: s_matnr for mara–matnr no intervals                        modif id I1. at selection-screen output.   if rb1 eq ‘X’.   loop at screen.     case screen–group1.       when ‘I1’.         screen–active = ‘1’.         modify screen.     endcase.   endloop.   else.   loop at screen.     case screen–group1.       when ‘I1’.         screen–active = ‘0’.         modify screen.     endcase.   endloop.   endif.