private Widget _prepareMappingMetadata(final int row, final MappingAssoc ma) {
Image img = VineMain.images.metadata().createImage();
final DisclosurePanel disclosure = new DisclosurePanel(img); // DisclosurePanel("");
disclosure.setTitle("Mapping metadata");
disclosure.addEventHandler(new DisclosureHandler() {
public void onClose(DisclosureEvent event) {
flexPanel.setText(row + 1, 0, "");
// Note: we can release the metadata panel as any value change there
// is captured in the corresponding entry in the mapping's metadata map.
ma.mdPanel = null;