sclass BackgroundProcessesUI<A> {
  Set<A> processes = syncLinkedHashSet();
  SimpleLiveValue<Int> lvCount = new SimpleLiveValue<Int>(Int, 0);
  
  JLabel shortLabel() {
    ret transformedLiveValueLabel(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));
  }
}