progress bar to update as script runs

Hi, I'd like to have a progress bar being displayed as my script runs. I created a simple progress bar as follows:

var win = new Window("palette", "SnpCreateProgressBar", [150, 150, 600, 260]); 
win.pnl = win.add("panel", [10, 10, 440, 100], "Script Progress");
win.pnl.progBar = win.pnl.add("progressbar", [20, 35, 410, 60], 0, 100);
win.pnl.progBarLabel = win.pnl.add("statictext", [20, 20, 320, 35], "0%");
win.show();
                    while(win.pnl.progBar.value < win.pnl.progBar.maxvalue)
                    {
                              // this is what causes the progress bar increase its progress
                              win.pnl.progBar.value++; 
            win.pnl.progBarLabel.text = win.pnl.progBar.value+"%";
                              $.sleep(10);
                    }
    alert('Done!'); 
win.close();

Now, if I target the ExtendScript Toolkit, I can see the "animation" of the bar progressing. But If I target illustrator, I only see when it's at 0% and then it jump to 100%. Is there a way to update the information visually as the script progresses?

Thanks!

I'm running CS6 on mac.