docs: public String getDefaultScreenKeyArea()
      {
          for (int i = DBConstants.MAIN_KEY_AREA; i < this.getKeyAreaCount(); i++)
          {
              if (this.getKeyArea(i).getUniqueKeyCode() == DBConstants.NOT_UNIQUE)
                  if (this.getKeyArea(i).getKeyField(DBConstants.MAIN_KEY_FIELD).getField(DBConstants.FILE_KEY_AREA) instanceof StringField)
                      return this.getKeyArea(i).getKeyName();
          }
          return null;      // Return the current key area
      }