When I add my own lt.png file in
Code:
Library/Preferences/calibre/resources/images
, it does appear as a dock icon
when Calibre is not working. However, the moment Calibre is up and running, it reverts to its default icon.
Moreover, I tried manually replacing the calibre.icns icon inside the calibre package in Applications, and it refused to start - which leads me to believe there is some checksum verification or something. At any rate, this is rather bizzarre, if you ask me, because I've done this for other applications like Skype and they work fine.
Bottom line, how difficult would it be to make the default application icon in line with the macOS style?