does not respond to the keyboard. It is perfectly possible to get to this from the windows start menu using just the keyboard, but it cannot be dismissed using the enter key (which ought to be possible).
Indeed, the "OK" button of that dialog is not automatically focused and that is why the "Enter" keyboard button does not close it. In order to close it you need to first move the focus on the "OK" button using the "Tab" keyboard button and then press the "Enter" key.
I added this improvement on our TODO list and it will be available in a future version of Advanced Installer. Thank you for your suggestion.