I agree with everything @Silvio_Grosso because I have said it before. 
To add to that, something I mentioned a while ago but can’t locate in the forum: When I close the open window without opening a file, I am left with an empty PhotoFlow main window and console. There is no UI besides the window title bar: my only option is to close the app. Cancel or close should quit the app.
From time to time, I complain about lens correction’s distortion not doing it right. I tend to keep it off because of that, but sometimes I am curious to see what it does. E.g., for [Play Raw] Sacre Coeur → Backlight challenge, the edges on either side get stretched out even more. Doesn’t feel natural, so I turned it back off.