<pre>  /**
   * The constants used in this Content Widget.
   */
  public static interface CwConstants extends Constants {
    String cwCellValidationColumnAddress();

    String cwCellValidationColumnName();

    String cwCellValidationDescription();

    String cwCellValidationError();

    String cwCellValidationName();
  }

  /**
   * An input cell that changes color based on the validation status.
   */
  private static class ValidatableInputCell extends
      AbstractInputCell&lt;String, ValidationDat