Sorry again: I just posted that I found the solution for that issue (including the solution itself) 11 minutes before your post I'm just replying to. Looks like we encountered some kind of synchronisation problem here. Maybe we should use some kind of semaphore or the like? I hope you read this one in time before you waste any time.You can disable the 'X' button. Not sure how off the top of my head, but I'll look in google in a minute.
I 100% agree when it comes to the X button. But is this really appropriate (or even required) for a button explicitly labelled "Cancel"?The user prompt to verify canceling isn't like a "are you really sure?". It's pretty much the standard when cancelling a long running operation in this manner. If you don't have it, your users will be pissed when they thought the 'X' would merely hide the progress dialog.