ecdave: first really like your app. thank you. Suggestion: It would be nice if a log was kept of missed problems as often a miss can expose a general weakness in reading, a blind spot if you will, a person needs to go over many times.
Maybe add a button to write to a 2nd log log that will record the pblm. Maybe even allowing user to enter a personal comment and ideally even mark the pblm with some other color meaning - user has marked as important.
Simple txt files add very little in terms of storage requirements. I have no idea how much extra complexity it might require programatically for app.
best ecdave 30aug2020, 21:16 ect
It becomes seki. https://senseis.xmp.net/?Seki