HI Praveer.
i am sure you will meet ur requirement. do as follows..
in side the handle usercommand event.
case e_ucomm.
when 'f-code'.
CALL METHOD g_grid_solopos->get_frontend_fieldcatalog
IMPORTING
et_fieldcatalog = lit_fcat[].
LOOP AT lit_fcat ASSIGNING <lfs_fcat>.
IF <lfs_fcat>-fieldname = 'DECO_TABLE' .
<lfs_fcat>-edit = c_x.
ENDIF.
ENDLOOP.
CALL METHOD g_grid_solopos->set_frontend_fieldcatalog
EXPORTING
it_fieldcatalog = lit_fcat[].
ENDcase