too easy to accidentally not post a generated key

After ~30 minutes spent generating a new key through the web interface, I accidentally clicked outside of the modal dialog instead of the submit button. AFAICT, this means that all the key generation work was for naught.

Side note: the presence of the "encrypt" progress bar when someone is trying to generate a new key but not encrypt anything is confusing.

Side side note: key generation happens in the main thread in Firefox, which freezes the entire browser for a long time.

Start by reproducing key generation through the web interface in Firefox, focusing on the modal dismissal, the encryption progress bar, and the browser freeze during generation. Trace the modal and generation entry points to determine whether these are separate fixes; done means generation work is not lost on accidental dismissal, progress reflects the selected operation, and the interface remains responsive.

Written by the indexing model from the issue text.