/** @see com.iver.andami.plugins.IExtension#isEnabled() */
  public boolean isEnabled() {
    IWindow v = PluginServices.getMDIManager().getActiveWindow();
    if (!(v instanceof Table)) {
      return false;
    }
    IEditableSource ies = ((Table) v).getModel().getModelo();
    if (!(ies instanceof IWriteable)) {
      return false;
    }
    IWriter writer = ((IWriteable) ies).getWriter();
    if (writer == null) {
      return false;
    }
    if (!writer.canAlterTable()) {
      return false;
    }

    return true;
  }