anchor.diff:  
     METHOD on_event.
   
  -    DATA: lx_exception TYPE REF TO lcx_exception.
  -
  +    DATA: lx_exception TYPE REF TO lcx_exception,
  +          li_page      TYPE REF TO lif_gui_page,
  +          lv_state     TYPE i.
   
       TRY.
  -        mi_cur_page->on_event(
  -          iv_action      = action
  -          iv_frame       = frame
  -          iv_getdata     = getdata
  -          it_postdata    = postdata
  -          it_query_table = query_table ).
  +        IF mi_cur_page IS BOUND.
  +          lv_state = mi_cur_page->on_event(
  +            iv_action      = action
  +            iv_frame       = frame
  +            iv_getdata     = getdata
  +            it_postdata    = postdata
  +            it_query_table = query_table ).
  +        ENDIF.
  +
  +        IF lv_state IS INITIAL.
  +          mo_router->on_event(
  +            EXPORTING
  +              iv_action      = action
  +              iv_frame       = frame
  +              iv_getdata     = getdata
  +              it_postdata    = postdata
  +              it_query_table = query_table
  +            IMPORTING
  +              eo_page        = li_page
  +              ev_state       = lv_state ).
  +        ENDIF.
  +
  +        CASE lv_state.
  +          WHEN gc_event_state-re_render.
  +            render( ).
  +          WHEN gc_event_state-new_page.
  +            call_page( li_page ).
  +          WHEN gc_event_state-go_back.
  +            back( ).
  +          WHEN OTHERS.
  +            _raise 'Unknown action'.
  +        ENDCASE.
  +
         CATCH lcx_exception INTO lx_exception.
           ROLLBACK WORK.
           MESSAGE lx_exception->mv_text TYPE 'S' DISPLAY LIKE 'E'.
  
positive.code: CLASS lcl_gui_page_db_display DEFINITION FINAL INHERITING FROM lcl_gui_page_super.
  
    PUBLIC SECTION.
      METHODS lif_gui_page~on_event REDEFINITION.
      METHODS lif_gui_page~render   REDEFINITION.
  
      METHODS: constructor
  
negative.code:   ENDMETHOD.
  
    METHOD go_home.
  
      on_event( action = 'home' ).
  
    ENDMETHOD.
  
    METHOD startup.
  
  