static S renderUserThreadsWithStackTraces() {
  ret renderUserThreadsWithStackTraces(Thread.getAllStackTraces());
}

static S renderUserThreadsWithStackTraces(Map<Thread, StackTraceElement[]> threadMap) {
  ret renderUserThreadsWithStackTraces(threadMap, "user thread");
}

static S renderUserThreadsWithStackTraces(Map<Thread, StackTraceElement[]> threadMap, S threadDescription) {
  new StringBuilder buf;
  int n = 0;
  for (Thread t : threadMap.keySet()) {
    ThreadGroup g = t.getThreadGroup();
    if (g != null && g.getName().equals("system")) continue;
    ++n;
    printTo(buf, t);
    for (StackTraceElement e : threadMap.get(t)) {
      printTo(buf, "  " + e);
    }
    printTo(buf);
  }
  printTo(buf, n(n, threadDescription) + ".");
  ret asciiHeading2(n(n, threadDescription) + " (+" + (l(threadMap)-n)  + ")") + "\n" + buf;
}

Began life as a copy of #1010502