How to clear data on ENTER from keyboard?

Question

I have an editable ALV .
When I input the material number and press ENTER button on keyboard, it populates some more fields in the row.
using    
CALL METHOD lo_grid->register_edit_event
      EXPORTING
        i_event_id = cl_gui_alv_grid=>mc_evt_enter.
I am able to trigger this in the event data_changed.
Now:;
I clear the material number and press ENTER again - it does not wipe out the fields that are filled in as above.
[This however works fine in debug mode..]
How to resolve this:
Here is my code:
In top-of-page event:
CALL METHOD lo_grid->register_edit_event
      EXPORTING
        i_event_id = cl_gui_alv_grid=>mc_evt_enter.
Then in
*       METHOD data_changed                                           *
  METHOD data_changed.
    PERFORM d0100_event_data_changed USING er_data_changed
                                           e_onf4
                                           e_onf4_before
                                           e_onf4_after.
  ENDMETHOD.                    "data_changed
FORM d0100_event_data_changed USING er_data_changed TYPE REF
                                        TO cl_alv_changed_data_protocol
                                          e_onf4        TYPE char1
                                          e_onf4_before TYPE char1
                                          e_onf4_after  TYPE char1.
                                                            "#EC *
  LOOP AT er_data_changed->mt_good_cells INTO ls_good_cells.
    IF NOT ls_good_cells IS INITIAL.
CASE ls_good_cells-fieldname.
when 'MATNR'.
            ls_delta_cells-row_id = ls_good_cells-row_id.
            ls_delta_cells-fieldname = 'WERKS'.
            ls_delta_cells-value = '1111'.  "I am passign space when MATNR is initial
            APPEND ls_delta_cells TO lt_delta_cells.
endif.
          IF NOT lt_delta_cells[] IS INITIAL.
            l_frontend_only = 'X'.
            CALL METHOD lo_grid->set_delta_cells
              EXPORTING
                it_delta_cells  = lt_delta_cells
                i_modified      = 'X'
                i_frontend_only = l_frontend_only.
          ENDIF.
endcase.
LOOP AT er_data_changed->mt_good_cells INTO ls_good_cells.
Edited by: Julius Bussche on Jan 26, 2009 9:34 AM
Code tags added.

Answer 1

I found a work around for this - when MATNR is initial, I did a clear in the alv output table for that row and then did a refresh_table_display.
it worked.
I am leaving this open for sometime to see if any better solutions can be proposed..