This has just happened again, when I was re-entering the code that EiffelStudio had just trashed.

This time I made sure that the system had been successfully compiled before attempting the autocompletion. It happened at exactly the same place. I had entered this:

  my_cancel_button.select_actions.

I had used autocompletion to enter both parts of this. After the dot, I hit F1. Again the "unexpected error occurred".

This time I made a manual backup. When I restarted EiffelStudio and opened the class, it again asked me if I wanted to use the backup. I varied my responses this time, because there are a couple of stupid questions in there about the file having been modified in another editor. I avoided trashing the class this time. The above half-complete line of code was there, so I hit F1 again, and the same error occurred.

Obviously I'd better avoid autocompletion in this release!