Why does the 'Import Key File' button in Lubuntu 20.04 Software Sources | Authentication dialog not do anything?
I downloaded a key file for Geogebra's repository. I believe that when I click Preferences | Software Sources | Authentication | Add Key File, I should get a file dialog which lets me choose the key file. However nothing happens when I press the button.
I have never used this functionality before, so maybe I am doing something wrong. The manual glosses over the issue, which makes me very suspicious though.
I am using Lubuntu 20.04.
