@Override
    protected void onEnterKeyDown(final Context context, final Element parent, final Expander value,
                                  final NativeEvent event, final ValueUpdater<Expander> valueUpdater) {
        if (valueUpdater != null && value != null && !value.isLeaf()) {
            valueUpdater.update(value);
        }
    }
Get the maximum column width required to fit expander icons for all levels
stroom-core-client-widget/src/main/java/stroom/cell/expander/client/ExpanderCell.java