sclass TextChangingListCellRenderer extends DefaultListCellRenderer {
  O f; // func(S) -> S
  
  *(O *f) {}

  public Component getListCellRendererComponent(JList list, O value, int index, bool isSelected, bool cellHasFocus) {
    Component c = super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
    S s = strOrEmpty(value);
    setText(f == null ? value : str(callF(f, s)));
    ret c;
  }
}