code: public void setSelected(boolean newValue) {
          boolean oldValue = isSelected();
          isSelected = newValue;
          updateHeader();
          firePropertyChange("selected", oldValue, newValue);
      }
docs: This panel draws its title bar differently if it is selected, which may
  be used to indicate to the user that this panel has the focus, or should
  get more attention than other simple internal frames.
  
  @param newValue
  a boolean, where true means the frame is selected (currently
  active) and false means it is not