Is that It’s an asynchronous operation and you need to send messages in the form of events back to the UI thread. But it’s difficult to predict how much of the total percentage of progress you just finished in the small part it’s doing, since every part is doing something different or longer-taking. So it’ll jump and won’t be steady. Or, you make a fake one that goes steady and shows down at the end, or something similar. So, fake. :)