DNDListener listener = new DNDListener() {
@SuppressWarnings({"unchecked", "rawtypes"})
@Override
public void dragStart(DNDEvent e) {
TreePanel tree = ((TreePanel) e.getComponent());
ModelData sel = tree.getSelectionModel().getSelectedItem();
if (sel != null && tree.getStore().getParent(sel) == null) {
e.setCancelled(true);
e.getStatus().setStatus(false);
return;
}
super.dragStart(e);