}
});
WGPositioningMetaFieldDefinitionModel positioningMetaFieldDefinitionModel = new WGPositioningMetaFieldDefinitionModel(_model);
positioningMetaFieldDefinitionModel.addListener(new BeanChangedListener<WGMetaFieldDefinition>() {
public void changed(WGMetaFieldDefinition bean) {
_treeViewer.refresh(bean, true);
_model.fireModelChanged();
}
});