Have especially a look for the column item in structure gs_vtref:
DATA:
BEGIN OF gs_vtref,
vtref TYPE vvscpos-vtref,
gpart_new TYPE vvscpos-gpart,
gpart_old TYPE vvscpos-gpart,
icon TYPE icon_d,
END OF gs_vtref,
gt_vtref LIKE TABLE OF gs_vtref,
gr_table TYPE REF TO cl_salv_table.
* Fill the table somehow
gs_vtref-icon = icon_red_light.
append gs_vtref to gt_vtref.
* ...
CALL METHOD cl_salv_table=>factory
IMPORTING
r_salv_table = gr_table
CHANGING
t_table = gt_vtref.
gr_table->display( ).
Regards,
Ulrich