ListGrid and SelectItem type filter editor - keys instead of empty form

[janos.milus]

SmartGWT Pro 4.0-p / SmartClient Version: v9.0p_2013-10-01/Pro Deployment (built 2013-10-01)

I have a ListGrid with an SQL datasource. Thes Grid has a field, where I have to show strings instead of integer values:

statuszMap = new LinkedHashMap<String, String>();
statuszMap.put("1", "Jogosítóra vár");
statuszMap.put("2", "Forrásgazdára vár");
statuszMap.put("3", "Tervösszesítőre vár");
statuszMap.put("4", "Ellenőrre vár");
statuszMap.put("5" "Véglegesítőre vár" );
statuszMap.put("99", "Élesítve");

ListGridField statusz = new ListGridField("statusz_id"); //statusz_id is an integer field
statusz.setValueMap(statuszMap);
statusz.setTitle("Státusz");

It works, but when I turn on the grid's filter editor I get "1,2,3,4,5,99" string instead of empty line when there is no filter in this field. When I open down the filter field it show the right lines (empty lines + the values, not the keys), but selecting the empty line and clicking the filter icon brings back the "1,2,3,4,5,99" value.

This numbers have no meaning to the end user and I don't want to show them. How can I get empty filter editor field when there is no filter criteria in that field?