Writer can initially store checksums db, detect internet connection and once a day (or weekly) check for new versions/new distros checksums db updates, download it and replace old db.

After selecting iso, detecting known distribution and completion of iso verification process - program can compare detected distro checksum and checksum stored in local db of sums - and:
1) in case of success - 'Verified as valid ... ISO' text can appear without 'SHA256 Checksum' pop-up dialog;
2) in case of failure - 'ISO is invalid: Checksum did not match' pop-up window can appear without 'SHA256 Checksum' pop-up dialog;