EventListeners for backgroundTasks?

Question

I'd like to attach an eventListener to a backgroundTask (Document.asynchronousExport), and I can't seem to figure out what event types, if any, get sent there.
There is a BackgroundTask.addEventListener(), so that would tend to suggest there are events. None of these events seem to fire:
"beforeQuit", "afterQuit", "beforeNew", "afterNew", "beforeOpen", "afterOpen", "beforeClose", "afterClose", "beforeSave", "afterSave", "beforeSaveAs", "afterSaveAs", "beforeSaveACopy", "afterSaveACopy", "beforeRevert", "afterRevert", "beforePrint", "afterPrint", "beforeExport", "afterExport", "beforeImport", "afterImport."
I realize I can basically get the same result from using Document.addEventListener() with eventType afterExport. That's what I will do instead..
(Or I could use an idle event. But that would be a waste.)
I guess Marijan Tompa seemed to note this in Jan in this post: Re: How To Prevent Recursive (Vicious Circle) Events.
Any solutions? Or is this in fact just unimplemented? Has it been wishformed?
Thanks!

Answer 1

Well, apparently there is an internal InDesign background Task called "Check Links," about which there are a bunch of weird properties.
For instance, if I run this quick hack script:
$.writeln("\n\n"+new Date());
a={}; function v(){var b=app.backgroundTasks,i,t;
  for(i=b.length-1; i>=0;i--){
       t=b[i]; a[t.id]=[t.id,t.name,t.isValid,t.percentDone,
       t.documentName,t.parent.name,t.status]; }
  return b.length; }
$.writeln("len "+v());
// for (j=0; j<1; j++) { v(); $.sleep(1)}
for (j in a) { $.writeln(a[j]); }
From the ESTK I get ~75 tasks:
len 75
2023,Check Links,true,0,,Adobe InDesign,RUNNING
2022,Check Links,true,0,,Adobe InDesign,RUNNING
2021,Check Links,true,0,,Adobe InDesign,RUNNING
2020,Check Links,true,0,,Adobe InDesign,RUNNING
2019,Check Links,true,0,,Adobe InDesign,RUNNING
2018,Check Links,true,0,,Adobe InDesign,RUNNING
2017,Check Links,true,0,,Adobe InDesign,RUNNING
2016,Check Links,true,0,,Adobe InDesign,RUNNING
2015,Check Links,true,0,,Adobe InDesign,RUNNING
2014,Check Links,true,0,,Adobe InDesign,RUNNING
2013,Check Links,true,0,,Adobe InDesign,RUNNING
2012,Check Links,true,0,,Adobe InDesign,RUNNING
And the task numbers only seem to increment when I poll -- that is, when I read the app.backgroundTasks array.
But if I run it from my javascript shell (change $.writeln to print), I get almost nothing. If I remove the commened out line and use j<1000, then I get ~10 or 20 tasks overall (All of which look like the above). And if I run it from ID's Scripts panel, I get no tasks at all. Pretty goofy.
Anyhow, to answer my own question, I submittd the following wishform bug report:
Concise problem statement:
SCRIPTING: a BackgroundTask has a .addEventListener() method, but no
events are dispatched to it.
Steps to reproduce bug:
In JavaScript, try to attach an eventListener to a background
asynchronous file export, and observe that it never runs:
(function() {
    var
        doc=app.activeDocument,
        pdfFile=new File("~/Desktop/test.pdf"),
        task = doc.asynchronousExportFile(ExportFormat.PDF_TYPE,
            pdfFile, false),
        events = ["beforeQuit", "afterQuit", "beforeNew", "afterNew",
        "beforeOpen", "afterOpen", "beforeClose", "afterClose",
        "beforeSave", "afterSave", "beforeSaveAs", "afterSaveAs",
        "beforeSaveACopy", "afterSaveACopy", "beforeRevert",
        "afterRevert", "beforePrint", "afterPrint", "beforeExport",
        "afterExport", "beforeImport", "afterImport", "afterTask" ],
        i, listeners = [];
    for (i=0; i<events.length; i++) {
        try {
            listeners.push(task.addEventListener(events[i],
                function(e) { alert("Caught "+events[i]); }));
        } catch (e) {
            $.writeln("failed to install "+events[i]+" for"+e);
Results: All published event types are successfully added, but
  none are disaptched. "afterTask" is not supported.
Expected results: There should be an event that fires on a BackgroundTask.
Otherwise the addEventListener() method is pointless. If there are multiple
exports going on, it's necessary to be able to distinguish between them,
which is not available when listening for a document's afterExport event.