Important Note for Windows users: Stardock WindowBlinds can break Custom Dialogs
Tonight, I just noticed something that seems very important for Windows users. I recently installed Stardock's WindowBlinds (www.stardock.com). It's very popular and allows you to change window frames in various ways. What I noticed is that if you install certain themes (I only tried three of them), your Custom Dialogs have the Close Window button in the upper right corner. If the user hits that button, the Custom Dialog closes and executes the Default button as defined by that script step. If your Default button choice is not Cancel, this can have disastrous results, as you can surmise. Placing AllowUserAbort(Off) just before the Custom Dialog step has no effect here.
This seems important because any of your Windows users can install WindowBlinds and cause this problem!
To accomodate this, I'm in the process of rewriting all my Custom Dialogs so that the Default button is always Cancel. Never thought that would be necessary. Perhaps that's a good practice anyway.
I'm out of town for a week, just in case info is needed from the OP of this thread.