FilteredHeader

public class FilterableHeader extends Header<String>
{
    /**
     * Image resources.
     */
    public static interface Resources extends ClientBundle
    {
        ImageResource downArrow();
        ImageResource upArrow();
    }

    private static final Resources RESOURCES = GWT.create(Resources.class);
    private static final int IMAGE_WIDTH = 16;
    private static final String DOWN_ARROW = makeImage(RESOURCES.downArrow());
    private static final String UP_ARROW = makeImage(RESOURCES.upArrow());

    private static String makeImage(ImageResource resource)
    {
        AbstractImagePrototype proto = AbstractImagePrototype.create(resource);
        return proto.getHTML().replace("style='", "style='position:absolute;right:0px;top:0px;");
    }

    private String text;

    public FilterableHeader(String text)
    {
        super(makeMyCell());
        this.text = text;
    }

    @Override
    public String getValue()
    {
        return text;
    }

    public static CompositeCell makeMyCell()
    {
        final ArrayList<HasCell<Resource, ?>> cells = new ArrayList<HasCell<Resource, ?>>();
        cells.add(new NameCell());
        // TODO: add another cell for filtering

        return new CompositeCell<Resource>(cells);

    }

    public static class NameCell implements HasCell<Resource, String>
    {
        public NameCell()
        {
        }

        @Override
        public Cell<String> getCell()
        {
            return new ClickableTextCell();
        }

        @Override
        public FieldUpdater<Resource, String> getFieldUpdater()
        {
            return null;
        }

        @Override
        public String getValue(Resource resource)
        {
            return resource.getStafferName();
        }
    }


}