!7

// TODO: capture all of System.out/System.err

cmodule SystemPrintLog {
  int linesToShow = 100, interval = 250;
  
  transient Appendable log; // virtual NotifyingStringBuffer
  transient JTextArea ta;
  transient long changesSeen;
  
  start {
    if (dm_getBounds() == null) {
      print("Setting frame rect");
      dm_setBounds(this, 0, max(0, getHeight(dm_desktopPane())-200), 400, 200);
    }
    log = getCreator('print_log);
    doEvery(interval, r updateMe);
  }
  
  visualize {
    ret componentPopupMenuItems(jSection("SYSTEM LOG", ta = moveCaretToEnd(typeWriterTextArea_noUndo(str(log)))),
      "Clear", r { clearStringBuffer_gen(log) },
      "Copy to new window", r { showText("System Log", log) });
  }
  
  void unvisualize() { ta = null; }
  
  void update {
    if (ta == null) ret;
    Long changes = cast getOpt(log, 'changes);
    if (changes == null || neq(changes, changesSeen)) {
      if (changes != null) changesSeen = changes;
      setText(ta, extractLastNLinesOfString(linesToShow, str(log));
    }
  }
}

Began life as a copy of #1018866