code: public void init(BaseField field, BasePanel screenParent, BasePanel subScreen)
      {
          super.init(field);
          m_iCurrentScreenNo = -1;
          m_screenParent = screenParent;
          this.setCurrentSubScreen(subScreen);
      }
docs: Constructor.
  @param field The basefield owner of this listener (usually null and set on setOwner()).
  @param screenParent The parent screen of this sub-screen.
  @param subScreen The current sub-screen.