Does El Capitan OS X cause problems with script driven dialog boxes?

This problem has taken a large chunk of my time in the last couple of days.

I have been able to qualify the issue and the issue has started with the Introduction of El Capitan.

The issue with dialog boxes not closing properly can be demonstrated by doing the following steps

1. Open InDesign and Extend script.  Add the following to a testscript:
     var w = new Window('dialog', 'Descriptions');
     btn = w.add('button', undefined, 'close');
     btn.onClick = function() {

             w.close();

             // the window should be closed when the alert is pops up.

              alert('foo’);

          }

          w.show();

          // the window show be closed if the you set a break point here.
          var a = 10;

          var c = 10;
          When running the script, will see that the dialog with the 'close' button closes before the alert dialog pops up.  This is the correct behavior.

2. Put the following at the top of the script:

#target "indesign"

Re run the script. You will see that the dialog with the close button does not close and the alert dialog pops up.  This is the incorrect behavior.

3) Remove the # target line from the script.  When you run the script again, the incorrect behavior occurs again.

4) Closing ExtendScript  and reopening  it and InDesign will cause the correct behavior to be shown, if you re-run the script.

5) Removing the #target is not an option for applications. If you and you try to reference the document using:

     currentDoc = app.activeDocument;

current document value is undefined.

Any clues from anyone for a workaround?

This is the normal way to do it.  It has nothing to do with El Captain.

var w = new Window('dialog', 'Descriptions');
var doMyStuff = false;
btn = w.add('button', undefined, 'close');

btn.onClick = function() {
    w.close();
    doMyStuff = true
}
w.show();

if (!doMyStuff) exit();

alert('foo');

// the window

var a = 10;
var c = 10;

HTH

Trevor