I developed my current script with CS2 and everything worked fine, but when I tested it in CS5 a couple issues showed up that I think are bugs.
When I run my script in CS5 the ESTK debugger starts up automatically. After closing the ESTK window, it restarts again every time I do anything in my dialog, like clicking a control. It does this even with the debug level set to zero ($.level = 0;). The only way I found to stop it was to remove all $.writeln calls.
The other problem was with stacked control groups. When my dialog is first displayed all the stacked controls are visible. It's setup to display controls based on the selected item in a dropdown list, and worked fine in CS2. However, in CS5 it's as if all the list items are selected so all the controls are visible at the same time. I'm not sure why it did this because I had code that set the list selection in the dialog constructor. I had to add code to the dialog's onShow function that re-selects the initial list item.