sclass BackgroundProcessesUI<A> {
  Set<A> processes = syncLinkedHashSet();
  SimpleLiveValue<Int> lvCount = new SimpleLiveValue<Int>(Int, 0);
  
  JLabel shortLabel() {
    ret bindToolTipToTransformedLiveValue(
      n -> makeToolTip(), lvCount,
        transformedLiveValueLabel_noAutoToolTip(n -> n2(n), lvCount));
  }
  
  void add(A process) {
    if (processes.add(process))
      lvCount.set(l(processes));
  }
  
  void remove(A process) {
    if (processes.remove(process))
      lvCount.set(l(processes));
  }
  
  S makeToolTip() {
    var l = cloneList(processes);
    ret empty(l) ? "No background processes"
      : n2(n, "background process", "background processes")
      + ": " + joinWithComma(processes);
  }
}