focus-restore not defined

Solved it by extending FilterForm:

public class FilterForm extends
org.apache.wicket.extensions.markup.html.repeater.data.table.filter.FilterForm
{
private static final long serialVersionUID = 1L;
public FilterForm(String id, IFilterStateLocator locator) {
super(id, locator);
super.remove("focus-restore");

add(new AbstractBehavior() {
private static final long serialVersionUID = 1L;
@Override
public void renderHead(IHeaderResponse response) {
super.renderHead(response);

response.renderOnDomReadyJavascript("_filter_focus_restore('"
+getFocusTrackerFieldCssId()+ "');");
}
});
}
}